diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index c6b840b..3a0f131 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -57,55 +57,33 @@ jobs:
           # Many composer dependencies need PHP 7.2+
           - php_version: "7.2"
             swoole_version: "4.6.7"
-            enable_zend_observer: "Off"
             cargo_features: ""
           - php_version: "7.3"
             swoole_version: "4.7.1"
-            enable_zend_observer: "Off"
             cargo_features: ""
           - php_version: "7.4"
             swoole_version: "4.8.10"
-            enable_zend_observer: "Off"
             cargo_features: ""
           - php_version: "8.0"
             swoole_version: "5.0.0"
-            enable_zend_observer: "Off"
-            cargo_features: ""
-          - php_version: "8.0"
-            swoole_version: "5.0.0"
-            enable_zend_observer: "On"
-            cargo_features: ""
-          - php_version: "8.1"
-            swoole_version: "5.1.1"
-            enable_zend_observer: "Off"
             cargo_features: ""
           - php_version: "8.1"
             swoole_version: "5.1.1"
-            enable_zend_observer: "On"
             cargo_features: ""
           - php_version: "8.2"
             swoole_version: "5.1.1"
-            enable_zend_observer: "Off"
             cargo_features: ""
           - php_version: "8.2"
             swoole_version: "5.1.1"
-            enable_zend_observer: "On"
-            cargo_features: ""
-          - php_version: "8.2"
-            swoole_version: "5.1.1"
-            enable_zend_observer: "On"
             cargo_features: "--features kafka-reporter"
           - php_version: "8.3"
             swoole_version: "5.1.1"
-            enable_zend_observer: "Off"
             cargo_features: ""
           - php_version: "8.4"
             swoole_version: "5.1.1"
-            enable_zend_observer: "Off"
             cargo_features: ""
           - php_version: "8.5"
-            swoole_version: "6.1.4"
-            enable_zend_observer: "Off"
+            swoole_version: "5.1.1"
             cargo_features: ""
 
     runs-on: ${{ matrix.os }}
@@ -201,8 +179,6 @@ jobs:
         id: cargo-test-step
         run: |
           cargo test --release --workspace ${{ matrix.flag.cargo_features }}
-        env:
-          ENABLE_ZEND_OBSERVER: ${{ matrix.flag.enable_zend_observer }}
         continue-on-error: true
 
       # Rebuild the mixture when cargo test failed.
@@ -222,8 +198,6 @@ jobs:
         if: steps.cargo-test-step.outcome != 'success'
         run: |
           cargo test --release --workspace
-        env:
-          ENABLE_ZEND_OBSERVER: ${{ matrix.flag.enable_zend_observer }}
 
       - name: View logs
         if: always()
diff --git a/docs/en/configuration/ini-settings.md b/docs/en/configuration/ini-settings.md
index fbd9c5c..214677e 100644
--- a/docs/en/configuration/ini-settings.md
+++ b/docs/en/configuration/ini-settings.md
@@ -19,7 +19,7 @@ This is the configuration list supported in `php.ini`.
 | skywalking_agent.ssl_cert_chain_path             | The certificate file. Enable mTLS when `ssl_key_path` and `ssl_cert_chain_path` exist. Only available when `reporter_type` is `grpc`.                                                                                                             |                           |
 | skywalking_agent.heartbeat_period                | Agent heartbeat report period. Unit, second.                                                                                                                                                                                                      | 30                        |
 | skywalking_agent.properties_report_period_factor | The agent sends the instance properties to the backend every heartbeat_period * properties_report_period_factor seconds.                                                                                                                          | 10                        |
-| skywalking_agent.enable_zend_observer            | Whether to use `zend observer` instead of `zend_execute_ex` to hook the functions, this feature is only available for PHP8+.                                                                                                                      | Off                       |
+| skywalking_agent.enable_zend_observer            | Whether to use `zend observer` instead of `zend_execute_ex` to hook the functions, this feature is only available for PHP8+.                                                                                                                      | On                        |
 | skywalking_agent.reporter_type                   | Reporter type, optional values are `grpc`, `kafka` and `standalone`.                                                                                                                                                                              | grpc                      |
 | skywalking_agent.kafka_bootstrap_servers         | A list of host/port pairs to use for connect to the Kafka cluster. Only available when `reporter_type` is `kafka`.                                                                                                                                |                           |
 | skywalking_agent.kafka_producer_config           | Configure Kafka Producer configuration in JSON format `{"key": "value}`. Only available when `reporter_type` is `kafka`.                                                                                                                          | {}                        |
diff --git a/docs/en/configuration/zend-observer.md b/docs/en/configuration/zend-observer.md
index c6deeb8..1027b34 100644
--- a/docs/en/configuration/zend-observer.md
+++ b/docs/en/configuration/zend-observer.md
@@ -2,7 +2,7 @@
 
 > Refer to: <https://www.datadoghq.com/blog/engineering/php-8-observability-baked-right-in/#the-observability-landscape-before-php-8>
 
-By default, skywalking-php hooks the `zend_execute_internal` and `zend_execute_ex` functions to implement auto instrumentation.
+On PHP 7, skywalking-php hooks the `zend_execute_internal` and `zend_execute_ex` functions to implement auto instrumentation.
 
 But there are some drawbacks:
 
@@ -28,5 +28,6 @@ opcache.jit = tracing
 [skywalking_agent]
 extension = skywalking_agent.so
 ; Switch to use zend observer api to implement auto instrumentation.
+; Default is On for PHP 8+.
 skywalking_agent.enable_zend_observer = On
 ```
diff --git a/src/lib.rs b/src/lib.rs
index 228f48e..1c6736f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -187,7 +187,7 @@ pub fn get_module() -> Module {
         10i64,
         Policy::System,
     );
-    module.add_ini(SKYWALKING_AGENT_ENABLE_ZEND_OBSERVER, false, Policy::System);
+    module.add_ini(SKYWALKING_AGENT_ENABLE_ZEND_OBSERVER, true, Policy::System);
     module.add_ini(
         SKYWALKING_AGENT_REPORTER_TYPE,
         "grpc".to_string(),
diff --git a/tests/common/mod.rs b/tests/common/mod.rs
index cea4285..8083027 100644
--- a/tests/common/mod.rs
+++ b/tests/common/mod.rs
@@ -70,7 +70,7 @@ pub const EXT: &str = if cfg!(target_os = "linux") {
 };
 
 pub static ENABLE_ZEND_OBSERVER: Lazy<String> =
-    Lazy::new(|| env::var("ENABLE_ZEND_OBSERVER").unwrap_or_else(|_| "Off".to_owned()));
+    Lazy::new(|| env::var("ENABLE_ZEND_OBSERVER").unwrap_or_else(|_| "On".to_owned()));
 
 pub static HTTP_CLIENT: Lazy<reqwest::Client> = Lazy::new(reqwest::Client::new);