diff --git a/CHANGES.md b/CHANGES.md
index 8f7c72976..d28d8ed40 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -49,6 +49,7 @@ Release Notes.
 #### Documentation
 
 * Add a section in `Log Collecting And Analysis` doc, introducing the new Python agent log reporter.
+* Add one missing step in `otel-receiver` doc about how to activate the default receiver.
 
 All issues and pull requests are [here](https://github.com/apache/skywalking/milestone/96?closed=1)
 
diff --git a/docs/en/setup/backend/backend-receivers.md b/docs/en/setup/backend/backend-receivers.md
index 42f323acf..c3e79a2bd 100644
--- a/docs/en/setup/backend/backend-receivers.md
+++ b/docs/en/setup/backend/backend-receivers.md
@@ -109,14 +109,19 @@ If the new configuration is not well-formed, the OAP may fail to start up. The f
 E.g. The `oc` handler loads rules from `$CLASSPATH/otel-oc-rules`.
 
 Supported handlers:
-    * `oc`: [OpenCensus](https://github.com/open-telemetry/opentelemetry-collector/blob/master/exporter/opencensusexporter/README.md) gRPC service handler.
+
+* `oc`: [OpenCensus](https://github.com/open-telemetry/opentelemetry-collector/blob/master/exporter/opencensusexporter/README.md) gRPC service handler.
+
+**Notice:**  Set `SW_OTEL_RECEIVER=default` through system environment or change `receiver-otel/selector=${SW_OTEL_RECEIVER:default}` to activate the OpenTelemetry receiver.
 
 The rule file should be in YAML format, defined by the scheme described in [prometheus-fetcher](./backend-fetcher.md).
 Note: `receiver-otel` only supports the `group`, `defaultMetricLevel`, and `metricsRules` nodes of the scheme due to its push mode.
 
 To activate the `oc` handler and relevant rules of `istio`:
+
 ```yaml
 receiver-otel:
+  // Change selector value to default, for activating the otel receiver.
   selector: ${SW_OTEL_RECEIVER:default}
   default:
     enabledHandlers: ${SW_OTEL_RECEIVER_ENABLED_HANDLERS:"oc"}
@@ -149,6 +154,9 @@ receiver-meter:
 ```
 
 To activate the meter rule files:
+
+Put your customized meter file xxx.yaml ( [mal](../../concepts-and-designs/mal.md) format) in the `config/meter-analyzer-config` directory and configure meteranalyzer `activefiles=${SW_ METER_ ANALYZER_ ACTIVE_ FILES:xxx}`
+
 ```yaml
 agent-analyzer:
   selector: ${SW_AGENT_ANALYZER:default}
diff --git a/docs/en/setup/backend/backend-vm-monitoring.md b/docs/en/setup/backend/backend-vm-monitoring.md
index 3093ee565..57e19e789 100644
--- a/docs/en/setup/backend/backend-vm-monitoring.md
+++ b/docs/en/setup/backend/backend-vm-monitoring.md
@@ -8,9 +8,11 @@ We define the VM entity as a `Service` in OAP, and use `vm::` as a prefix to ide
 2. The OpenTelemetry Collector fetches metrics from node-exporter via Prometheus Receiver and pushes metrics to the SkyWalking OAP Server via the OpenCensus gRPC Exporter.
 3. The SkyWalking OAP Server parses the expression with [MAL](../../concepts-and-designs/mal.md) to filter/calculate/aggregate and store the results. 
 
-## Setup 
-1. Set up [Prometheus node-exporter](https://prometheus.io/docs/guides/node-exporter/).
-2. Set up [OpenTelemetry Collector ](https://opentelemetry.io/docs/collector/). This is an example for OpenTelemetry Collector configuration [otel-collector-config.yaml](../../../../test/e2e/e2e-test/docker/promOtelVM/otel-collector-config.yaml).
+
+## Setup
+
+1. Setup [Prometheus node-exporter](https://prometheus.io/docs/guides/node-exporter/).
+2. Setup [OpenTelemetry Collector ](https://opentelemetry.io/docs/collector/). This is an example for OpenTelemetry Collector configuration [otel-collector-config.yaml](../../../../test/e2e/e2e-test/docker/promOtelVM/otel-collector-config.yaml).
 3. Config SkyWalking [OpenTelemetry receiver](backend-receivers.md#opentelemetry-receiver).
    
 ## Supported Metrics