diff --git a/CHANGES.md b/CHANGES.md
index a26d20f0c..2102ab6ea 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -29,6 +29,7 @@ Release Notes.
 * Fix kubernetes.client.opeanapi.ApiException.
 * Remove filename suffix in the meter active file config.
 * Introduce log analysis language (LAL).
+* Fix alarm httpclient connection leak.
 
 #### UI
 * Update selector scroller to show in all pages.
diff --git a/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/WebhookCallback.java b/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/WebhookCallback.java
index c997d6a25..96d8d9361 100644
--- a/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/WebhookCallback.java
+++ b/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/WebhookCallback.java
@@ -74,10 +74,11 @@ public class WebhookCallback implements AlarmCallback {
                 post.setHeader(HttpHeaders.CONTENT_TYPE, HttpHeaderValues.APPLICATION_JSON.toString());
 
                 StringEntity entity;
+                CloseableHttpResponse httpResponse = null;
                 try {
                     entity = new StringEntity(gson.toJson(alarmMessage), StandardCharsets.UTF_8);
                     post.setEntity(entity);
-                    CloseableHttpResponse httpResponse = httpClient.execute(post);
+                    httpResponse = httpClient.execute(post);
                     StatusLine statusLine = httpResponse.getStatusLine();
                     if (statusLine != null && statusLine.getStatusCode() != HttpStatus.SC_OK) {
                         log.error("send alarm to " + url + " failure. Response code: " + statusLine.getStatusCode());
@@ -86,6 +87,15 @@ public class WebhookCallback implements AlarmCallback {
                     log.error("Alarm to JSON error, " + e.getMessage(), e);
                 } catch (IOException e) {
                     log.error("send alarm to " + url + " failure.", e);
+                } finally {
+                    if (httpResponse != null) {
+                        try {
+                            httpResponse.close();
+                        } catch (IOException e) {
+                            log.error(e.getMessage(), e);
+                        }
+
+                    }
                 }
             });
         } finally {
diff --git a/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/dingtalk/DingtalkHookCallback.java b/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/dingtalk/DingtalkHookCallback.java
index 5acc63a80..e2ce79324 100644
--- a/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/dingtalk/DingtalkHookCallback.java
+++ b/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/dingtalk/DingtalkHookCallback.java
@@ -134,6 +134,7 @@ public class DingtalkHookCallback implements AlarmCallback {
      * Send alarm message to remote endpoint
      */
     private void sendAlarmMessage(CloseableHttpClient httpClient, String url, String requestBody) {
+        CloseableHttpResponse httpResponse = null;
         try {
             HttpPost post = new HttpPost(url);
             post.setConfig(requestConfig);
@@ -141,7 +142,7 @@ public class DingtalkHookCallback implements AlarmCallback {
             post.setHeader(HttpHeaders.CONTENT_TYPE, HttpHeaderValues.APPLICATION_JSON.toString());
             StringEntity entity = new StringEntity(requestBody, ContentType.APPLICATION_JSON);
             post.setEntity(entity);
-            CloseableHttpResponse httpResponse = httpClient.execute(post);
+            httpResponse = httpClient.execute(post);
             StatusLine statusLine = httpResponse.getStatusLine();
             if (statusLine != null && statusLine.getStatusCode() != HttpStatus.SC_OK) {
                 log.error("send dingtalk alarm to {} failure. Response code: {}, Response content: {}", url, statusLine.getStatusCode(),
@@ -149,6 +150,15 @@ public class DingtalkHookCallback implements AlarmCallback {
             }
         } catch (Throwable e) {
             log.error("send dingtalk alarm to {} failure.", url, e);
+        } finally {
+            if (httpResponse != null) {
+                try {
+                    httpResponse.close();
+                } catch (IOException e) {
+                    log.error(e.getMessage(), e);
+                }
+
+            }
         }
     }
 }
diff --git a/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/feishu/FeishuHookCallback.java b/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/feishu/FeishuHookCallback.java
index bff3a558f..02a9a3a75 100644
--- a/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/feishu/FeishuHookCallback.java
+++ b/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/feishu/FeishuHookCallback.java
@@ -153,6 +153,7 @@ public class FeishuHookCallback implements AlarmCallback {
      * Send alarm message to remote endpoint
      */
     private void sendAlarmMessage(CloseableHttpClient httpClient, String url, String requestBody) {
+        CloseableHttpResponse httpResponse = null;
         try {
             HttpPost post = new HttpPost(url);
             post.setConfig(requestConfig);
@@ -160,7 +161,7 @@ public class FeishuHookCallback implements AlarmCallback {
             post.setHeader(HttpHeaders.CONTENT_TYPE, HttpHeaderValues.APPLICATION_JSON.toString());
             StringEntity entity = new StringEntity(requestBody, ContentType.APPLICATION_JSON);
             post.setEntity(entity);
-            CloseableHttpResponse httpResponse = httpClient.execute(post);
+            httpResponse = httpClient.execute(post);
             StatusLine statusLine = httpResponse.getStatusLine();
             if (statusLine != null && statusLine.getStatusCode() != HttpStatus.SC_OK) {
                 log.error("send feishu alarm to {} failure. Response code: {}, Response content: {}", url, statusLine.getStatusCode(),
@@ -168,6 +169,15 @@ public class FeishuHookCallback implements AlarmCallback {
             }
         } catch (Throwable e) {
             log.error("send feishu alarm to {} failure.", url, e);
+        } finally {
+            if (httpResponse != null) {
+                try {
+                    httpResponse.close();
+                } catch (IOException e) {
+                    log.error(e.getMessage(), e);
+                }
+
+            }
         }
     }
 }
diff --git a/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/slack/SlackhookCallback.java b/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/slack/SlackhookCallback.java
index 95030a5aa..c51cbc57c 100644
--- a/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/slack/SlackhookCallback.java
+++ b/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/slack/SlackhookCallback.java
@@ -76,6 +76,7 @@ public class SlackhookCallback implements AlarmCallback {
                 post.setHeader(HttpHeaders.CONTENT_TYPE, HttpHeaderValues.APPLICATION_JSON.toString());
 
                 StringEntity entity;
+                CloseableHttpResponse httpResponse = null;
                 try {
                     JsonObject jsonObject = new JsonObject();
                     JsonArray jsonElements = new JsonArray();
@@ -88,7 +89,7 @@ public class SlackhookCallback implements AlarmCallback {
                     jsonObject.add("blocks", jsonElements);
                     entity = new StringEntity(GSON.toJson(jsonObject), ContentType.APPLICATION_JSON);
                     post.setEntity(entity);
-                    CloseableHttpResponse httpResponse = httpClient.execute(post);
+                    httpResponse = httpClient.execute(post);
                     StatusLine statusLine = httpResponse.getStatusLine();
                     if (statusLine != null && statusLine.getStatusCode() != HttpStatus.SC_OK) {
                         log.error("Send slack alarm to {} failure. Response code: {}", url , statusLine.getStatusCode());
@@ -97,6 +98,15 @@ public class SlackhookCallback implements AlarmCallback {
                     log.error("Alarm to JSON error, {} ", e.getMessage(), e);
                 } catch (IOException e) {
                     log.error("Send slack alarm to {} failure.", url , e);
+                } finally {
+                    if (httpResponse != null) {
+                        try {
+                            httpResponse.close();
+                        } catch (IOException e) {
+                            log.error(e.getMessage(), e);
+                        }
+
+                    }
                 }
             });
         } finally {
diff --git a/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/wechat/WechatHookCallback.java b/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/wechat/WechatHookCallback.java
index 9ac151778..24bd8ad08 100644
--- a/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/wechat/WechatHookCallback.java
+++ b/oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/wechat/WechatHookCallback.java
@@ -82,6 +82,7 @@ public class WechatHookCallback implements AlarmCallback {
     }
 
     private void sendAlarmMessage(CloseableHttpClient httpClient, String url, String requestBody) {
+        CloseableHttpResponse httpResponse = null;
         try {
             HttpPost post = new HttpPost(url);
             post.setConfig(requestConfig);
@@ -89,13 +90,22 @@ public class WechatHookCallback implements AlarmCallback {
             post.setHeader(HttpHeaders.CONTENT_TYPE, HttpHeaderValues.APPLICATION_JSON.toString());
             StringEntity entity = new StringEntity(requestBody, ContentType.APPLICATION_JSON);
             post.setEntity(entity);
-            CloseableHttpResponse httpResponse = httpClient.execute(post);
+            httpResponse = httpClient.execute(post);
             StatusLine statusLine = httpResponse.getStatusLine();
             if (statusLine != null && statusLine.getStatusCode() != HttpStatus.SC_OK) {
                 log.error("send wechat alarm to {} failure. Response code: {} ", url, statusLine.getStatusCode());
             }
         } catch (Throwable e) {
             log.error("send wechat alarm to {} failure.", url, e);
+        } finally {
+            if (httpResponse != null) {
+                try {
+                    httpResponse.close();
+                } catch (IOException e) {
+                    log.error(e.getMessage(), e);
+                }
+
+            }
         }
     }
 }