diff --git a/extensions/elasticsearch/ActiveQuery.php b/extensions/elasticsearch/ActiveQuery.php
index 5012761b89..21c9f69ccd 100644
--- a/extensions/elasticsearch/ActiveQuery.php
+++ b/extensions/elasticsearch/ActiveQuery.php
@@ -77,6 +77,11 @@ class ActiveQuery extends Query implements ActiveQueryInterface
     use ActiveQueryTrait;
     use ActiveRelationTrait;
 
+    /**
+     * @event Event an event that is triggered when the query is initialized via [[init()]].
+     */
+    const EVENT_INIT = 'init';
+
 
     /**
      * Constructor.
@@ -89,6 +94,18 @@ class ActiveQuery extends Query implements ActiveQueryInterface
         parent::__construct($config);
     }
 
+    /**
+     * Initializes the object.
+     * This method is called at the end of the constructor. The default implementation will trigger
+     * an [[EVENT_INIT]] event. If you override this method, make sure you call the parent implementation at the end
+     * to ensure triggering of the event.
+     */
+    public function init()
+    {
+        parent::init();
+        $this->trigger(self::EVENT_INIT);
+    }
+
     /**
      * Creates a DB command that can be used to execute this query.
      * @param Connection $db the DB connection used to create the DB command.
diff --git a/extensions/elasticsearch/ActiveRecord.php b/extensions/elasticsearch/ActiveRecord.php
index 4c0ed983c1..f11d986217 100644
--- a/extensions/elasticsearch/ActiveRecord.php
+++ b/extensions/elasticsearch/ActiveRecord.php
@@ -7,6 +7,7 @@
 
 namespace yii\elasticsearch;
 
+use Yii;
 use yii\base\InvalidCallException;
 use yii\base\InvalidConfigException;
 use yii\db\BaseActiveRecord;
@@ -71,7 +72,7 @@ class ActiveRecord extends BaseActiveRecord
      */
     public static function find()
     {
-        return new ActiveQuery(get_called_class());
+        return Yii::createObject(ActiveQuery::className(), [get_called_class()]);
     }
 
     /**
diff --git a/extensions/elasticsearch/CHANGELOG.md b/extensions/elasticsearch/CHANGELOG.md
index 22bbc46799..b9fd5f6d89 100644
--- a/extensions/elasticsearch/CHANGELOG.md
+++ b/extensions/elasticsearch/CHANGELOG.md
@@ -8,6 +8,7 @@ Yii Framework 2 elasticsearch extension Change Log
 - Bug #4187: Elasticsearch dynamic scripting is disabled in 1.2.0, so do not use it in query builder (cebe)
 - Enh #3520: Added `unlinkAll()`-method to active record to remove all records of a model relation (NmDimas, samdark, cebe)
 - Enh #3527: Added `highlight` property to Query and ActiveRecord. (Borales)
+- Enh #4048: Added `init` event to `ActiveQuery` classes (qiangxue)
 - Enh #4086: changedAttributes of afterSave Event now contain old values (dizews)
 - Enh: Make error messages more readable in HTML output (cebe)
 - Chg: asArray in ActiveQuery is now equal to using the normal Query. This means, that the output structure has changed and `with` is supported anymore. (cebe)
diff --git a/extensions/mongodb/ActiveQuery.php b/extensions/mongodb/ActiveQuery.php
index dd1d196d8a..8a50d086f1 100644
--- a/extensions/mongodb/ActiveQuery.php
+++ b/extensions/mongodb/ActiveQuery.php
@@ -64,6 +64,11 @@ class ActiveQuery extends Query implements ActiveQueryInterface
     use ActiveQueryTrait;
     use ActiveRelationTrait;
 
+    /**
+     * @event Event an event that is triggered when the query is initialized via [[init()]].
+     */
+    const EVENT_INIT = 'init';
+
 
     /**
      * Constructor.
@@ -76,6 +81,18 @@ class ActiveQuery extends Query implements ActiveQueryInterface
         parent::__construct($config);
     }
 
+    /**
+     * Initializes the object.
+     * This method is called at the end of the constructor. The default implementation will trigger
+     * an [[EVENT_INIT]] event. If you override this method, make sure you call the parent implementation at the end
+     * to ensure triggering of the event.
+     */
+    public function init()
+    {
+        parent::init();
+        $this->trigger(self::EVENT_INIT);
+    }
+
     /**
      * @inheritdoc
      */
diff --git a/extensions/mongodb/ActiveRecord.php b/extensions/mongodb/ActiveRecord.php
index de029890b4..7b5653b86b 100644
--- a/extensions/mongodb/ActiveRecord.php
+++ b/extensions/mongodb/ActiveRecord.php
@@ -7,6 +7,7 @@
 
 namespace yii\mongodb;
 
+use Yii;
 use yii\base\InvalidConfigException;
 use yii\db\BaseActiveRecord;
 use yii\db\StaleObjectException;
@@ -96,7 +97,7 @@ abstract class ActiveRecord extends BaseActiveRecord
      */
     public static function find()
     {
-        return new ActiveQuery(get_called_class());
+        return Yii::createObject(ActiveQuery::className(), [get_called_class()]);
     }
 
     /**
diff --git a/extensions/mongodb/CHANGELOG.md b/extensions/mongodb/CHANGELOG.md
index 00311361ee..ee2ebe99c0 100644
--- a/extensions/mongodb/CHANGELOG.md
+++ b/extensions/mongodb/CHANGELOG.md
@@ -9,6 +9,7 @@ Yii Framework 2 mongodb extension Change Log
 - Enh #3520: Added `unlinkAll()`-method to active record to remove all records of a model relation (NmDimas, samdark, cebe)
 - Enh #3778: Gii generator for Active Record model added (klimov-paul)
 - Enh #3947: Migration support added (klimov-paul)
+- Enh #4048: Added `init` event to `ActiveQuery` classes (qiangxue)
 - Enh #4086: changedAttributes of afterSave Event now contain old values (dizews)
 - Enh #4335: `yii\mongodb\log\MongoDbTarget` log target added (klimov-paul)
 
diff --git a/extensions/mongodb/file/ActiveQuery.php b/extensions/mongodb/file/ActiveQuery.php
index 80d456e22c..77bb03931e 100644
--- a/extensions/mongodb/file/ActiveQuery.php
+++ b/extensions/mongodb/file/ActiveQuery.php
@@ -40,6 +40,11 @@ class ActiveQuery extends Query implements ActiveQueryInterface
     use ActiveQueryTrait;
     use ActiveRelationTrait;
 
+    /**
+     * @event Event an event that is triggered when the query is initialized via [[init()]].
+     */
+    const EVENT_INIT = 'init';
+
 
     /**
      * Constructor.
@@ -52,6 +57,18 @@ class ActiveQuery extends Query implements ActiveQueryInterface
         parent::__construct($config);
     }
 
+    /**
+     * Initializes the object.
+     * This method is called at the end of the constructor. The default implementation will trigger
+     * an [[EVENT_INIT]] event. If you override this method, make sure you call the parent implementation at the end
+     * to ensure triggering of the event.
+     */
+    public function init()
+    {
+        parent::init();
+        $this->trigger(self::EVENT_INIT);
+    }
+
     /**
      * Executes query and returns all results as an array.
      * @param \yii\mongodb\Connection $db the Mongo connection used to execute the query.
diff --git a/extensions/mongodb/file/ActiveRecord.php b/extensions/mongodb/file/ActiveRecord.php
index 1a7f9bde97..1598b077c0 100644
--- a/extensions/mongodb/file/ActiveRecord.php
+++ b/extensions/mongodb/file/ActiveRecord.php
@@ -7,6 +7,7 @@
 
 namespace yii\mongodb\file;
 
+use Yii;
 use yii\base\InvalidParamException;
 use yii\db\StaleObjectException;
 use yii\web\UploadedFile;
@@ -49,7 +50,7 @@ abstract class ActiveRecord extends \yii\mongodb\ActiveRecord
      */
     public static function find()
     {
-        return new ActiveQuery(get_called_class());
+        return Yii::createObject(ActiveQuery::className(), [get_called_class()]);
     }
 
     /**
diff --git a/extensions/redis/ActiveQuery.php b/extensions/redis/ActiveQuery.php
index 2a1aff6c1d..5c0b92100c 100644
--- a/extensions/redis/ActiveQuery.php
+++ b/extensions/redis/ActiveQuery.php
@@ -77,6 +77,10 @@ class ActiveQuery extends Component implements ActiveQueryInterface
     use ActiveQueryTrait;
     use ActiveRelationTrait;
 
+    /**
+     * @event Event an event that is triggered when the query is initialized via [[init()]].
+     */
+    const EVENT_INIT = 'init';
 
     /**
      * Constructor.
@@ -89,6 +93,18 @@ class ActiveQuery extends Component implements ActiveQueryInterface
         parent::__construct($config);
     }
 
+    /**
+     * Initializes the object.
+     * This method is called at the end of the constructor. The default implementation will trigger
+     * an [[EVENT_INIT]] event. If you override this method, make sure you call the parent implementation at the end
+     * to ensure triggering of the event.
+     */
+    public function init()
+    {
+        parent::init();
+        $this->trigger(self::EVENT_INIT);
+    }
+
     /**
      * Executes the query and returns all results as an array.
      * @param Connection $db the database connection used to execute the query.
diff --git a/extensions/redis/ActiveRecord.php b/extensions/redis/ActiveRecord.php
index aa7691fc48..6993126b9d 100644
--- a/extensions/redis/ActiveRecord.php
+++ b/extensions/redis/ActiveRecord.php
@@ -7,6 +7,7 @@
 
 namespace yii\redis;
 
+use Yii;
 use yii\base\InvalidConfigException;
 use yii\db\BaseActiveRecord;
 use yii\helpers\Inflector;
@@ -53,7 +54,7 @@ class ActiveRecord extends BaseActiveRecord
      */
     public static function find()
     {
-        return new ActiveQuery(get_called_class());
+        return Yii::createObject(ActiveQuery::className(), [get_called_class()]);
     }
 
     /**
diff --git a/extensions/redis/CHANGELOG.md b/extensions/redis/CHANGELOG.md
index d80029907c..77df7bba99 100644
--- a/extensions/redis/CHANGELOG.md
+++ b/extensions/redis/CHANGELOG.md
@@ -5,6 +5,7 @@ Yii Framework 2 redis extension Change Log
 --------------------------
 
 - Enh #3520: Added `unlinkAll()`-method to active record to remove all records of a model relation (NmDimas, samdark, cebe)
+- Enh #4048: Added `init` event to `ActiveQuery` classes (qiangxue)
 - Enh #4086: changedAttributes of afterSave Event now contain old values (dizews)
 
 
diff --git a/extensions/sphinx/ActiveQuery.php b/extensions/sphinx/ActiveQuery.php
index f2e87d7520..ee3a405b5b 100644
--- a/extensions/sphinx/ActiveQuery.php
+++ b/extensions/sphinx/ActiveQuery.php
@@ -85,6 +85,11 @@ class ActiveQuery extends Query implements ActiveQueryInterface
     use ActiveQueryTrait;
     use ActiveRelationTrait;
 
+    /**
+     * @event Event an event that is triggered when the query is initialized via [[init()]].
+     */
+    const EVENT_INIT = 'init';
+
     /**
      * @var string the SQL statement to be executed for retrieving AR records.
      * This is set by [[ActiveRecord::findBySql()]].
@@ -103,6 +108,18 @@ class ActiveQuery extends Query implements ActiveQueryInterface
         parent::__construct($config);
     }
 
+    /**
+     * Initializes the object.
+     * This method is called at the end of the constructor. The default implementation will trigger
+     * an [[EVENT_INIT]] event. If you override this method, make sure you call the parent implementation at the end
+     * to ensure triggering of the event.
+     */
+    public function init()
+    {
+        parent::init();
+        $this->trigger(self::EVENT_INIT);
+    }
+
     /**
      * Sets the [[snippetCallback]] to [[fetchSnippetSourceFromModels()]], which allows to
      * fetch the snippet source strings from the Active Record models, using method
diff --git a/extensions/sphinx/ActiveRecord.php b/extensions/sphinx/ActiveRecord.php
index 97bf63b04a..7020f99279 100644
--- a/extensions/sphinx/ActiveRecord.php
+++ b/extensions/sphinx/ActiveRecord.php
@@ -140,7 +140,7 @@ abstract class ActiveRecord extends BaseActiveRecord
      */
     public static function find()
     {
-        return new ActiveQuery(get_called_class());
+        return Yii::createObject(ActiveQuery::className(), [get_called_class()]);
     }
 
     /**
diff --git a/extensions/sphinx/CHANGELOG.md b/extensions/sphinx/CHANGELOG.md
index 88eef3c071..dff9ecb733 100644
--- a/extensions/sphinx/CHANGELOG.md
+++ b/extensions/sphinx/CHANGELOG.md
@@ -7,6 +7,7 @@ Yii Framework 2 sphinx extension Change Log
 - Bug #3668: Escaping of the special characters at 'MATCH' statement added (klimov-paul)
 - Bug #4018: AR relation eager loading does not work with db models (klimov-paul)
 - Enh #3520: Added `unlinkAll()`-method to active record to remove all records of a model relation (NmDimas, samdark, cebe)
+- Enh #4048: Added `init` event to `ActiveQuery` classes (qiangxue)
 - Enh #4086: changedAttributes of afterSave Event now contain old values (dizews)
 - Enh: Added support for using sub-queries when building a DB query with `IN` condition (qiangxue)
 - Chg #2287: Split `yii\sphinx\ColumnSchema::typecast()` into two methods `phpTypecast()` and `dbTypecast()` to allow specifying PDO type explicitly (cebe)
diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index 728aeeded0..610fd170dd 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -130,6 +130,7 @@ Yii Framework 2 Change Log
     - Added note about the fact that intl is required for non-latin languages to requirements checker.
 - Enh #3992: In mail layouts you can now access the message object via `$message` variable (qiangxue)
 - Enh #4028: Added ability to `yii\widgets\Menu` to encode each item's label separately (creocoder, umneeq)
+- Enh #4048: Added `init` event to `ActiveQuery` classes (qiangxue)
 - Enh #4072: `\yii\rbac\PhpManager` adjustments (samdark)
     - Data is now stored in three separate files for items, assignments and rules. File format is simpler.
     - Removed `authFile`. Added `itemFile`, `assignmentFile` and `ruleFile`.
diff --git a/framework/db/ActiveQuery.php b/framework/db/ActiveQuery.php
index b928f31880..06778f7acc 100644
--- a/framework/db/ActiveQuery.php
+++ b/framework/db/ActiveQuery.php
@@ -72,6 +72,11 @@ class ActiveQuery extends Query implements ActiveQueryInterface
     use ActiveQueryTrait;
     use ActiveRelationTrait;
 
+    /**
+     * @event Event an event that is triggered when the query is initialized via [[init()]].
+     */
+    const EVENT_INIT = 'init';
+
     /**
      * @var string the SQL statement to be executed for retrieving AR records.
      * This is set by [[ActiveRecord::findBySql()]].
@@ -102,6 +107,18 @@ class ActiveQuery extends Query implements ActiveQueryInterface
         parent::__construct($config);
     }
 
+    /**
+     * Initializes the object.
+     * This method is called at the end of the constructor. The default implementation will trigger
+     * an [[EVENT_INIT]] event. If you override this method, make sure you call the parent implementation at the end
+     * to ensure triggering of the event.
+     */
+    public function init()
+    {
+        parent::init();
+        $this->trigger(self::EVENT_INIT);
+    }
+
     /**
      * Executes query and returns all results as an array.
      * @param Connection $db the DB connection used to create the DB command.
diff --git a/framework/db/ActiveRecord.php b/framework/db/ActiveRecord.php
index 51ccaa4113..2025ca4de9 100644
--- a/framework/db/ActiveRecord.php
+++ b/framework/db/ActiveRecord.php
@@ -258,7 +258,7 @@ class ActiveRecord extends BaseActiveRecord
      */
     public static function find()
     {
-        return new ActiveQuery(get_called_class());
+        return Yii::createObject(ActiveQuery::className(), [get_called_class()]);
     }
 
     /**