diff --git a/dolphinscheduler-api/src/main/java/org/apache/dolphinscheduler/api/service/impl/ProcessTaskRelationServiceImpl.java b/dolphinscheduler-api/src/main/java/org/apache/dolphinscheduler/api/service/impl/ProcessTaskRelationServiceImpl.java
index 9a476c8e8bfcfcaef78cd20c4ad402385ee747fa..d4e79bf35063b012a28893724531ccffc0626131 100644
--- a/dolphinscheduler-api/src/main/java/org/apache/dolphinscheduler/api/service/impl/ProcessTaskRelationServiceImpl.java
+++ b/dolphinscheduler-api/src/main/java/org/apache/dolphinscheduler/api/service/impl/ProcessTaskRelationServiceImpl.java
@@ -22,6 +22,7 @@ import org.apache.dolphinscheduler.api.exceptions.ServiceException;
 import org.apache.dolphinscheduler.api.service.ProcessTaskRelationService;
 import org.apache.dolphinscheduler.api.service.ProjectService;
 import org.apache.dolphinscheduler.common.Constants;
+import org.apache.dolphinscheduler.common.enums.TaskType;
 import org.apache.dolphinscheduler.dao.entity.ProcessDefinition;
 import org.apache.dolphinscheduler.dao.entity.ProcessTaskRelation;
 import org.apache.dolphinscheduler.dao.entity.ProcessTaskRelationLog;
@@ -191,15 +192,57 @@ public class ProcessTaskRelationServiceImpl extends BaseServiceImpl implements P
     /**
      * delete process task relation
      *
-     * @param loginUser login user
-     * @param projectCode project code
+     * @param loginUser             login user
+     * @param projectCode           project code
      * @param processDefinitionCode process definition code
-     * @param taskCode the post task code
+     * @param taskCode              the post task code
      * @return delete result code
      */
     @Override
     public Map<String, Object> deleteTaskProcessRelation(User loginUser, long projectCode, long processDefinitionCode, long taskCode) {
-        return null;
+        Project project = projectMapper.queryByCode(projectCode);
+        //check user access for project
+        Map<String, Object> result = projectService.checkProjectAndAuth(loginUser, project, projectCode);
+        if (result.get(Constants.STATUS) != Status.SUCCESS) {
+            return result;
+        }
+        if (taskCode == 0) {
+            putMsg(result, Status.DELETE_TASK_PROCESS_RELATION_ERROR);
+            return result;
+        }
+        List<ProcessTaskRelation> downstreamList = processTaskRelationMapper.queryByCode(projectCode, processDefinitionCode, taskCode, 0L);
+        if (CollectionUtils.isNotEmpty(downstreamList)) {
+            Set<Long> postTaskCodes = downstreamList
+                    .stream()
+                    .map(ProcessTaskRelation::getPostTaskCode)
+                    .collect(Collectors.toSet());
+            putMsg(result, Status.TASK_HAS_DOWNSTREAM, org.apache.commons.lang.StringUtils.join(postTaskCodes, ","));
+            return result;
+        }
+
+        ProcessTaskRelationLog processTaskRelationLog = new ProcessTaskRelationLog();
+        processTaskRelationLog.setProjectCode(projectCode);
+        processTaskRelationLog.setPreTaskCode(taskCode);
+        processTaskRelationLog.setProcessDefinitionCode(processDefinitionCode);
+        int deleteRelation = processTaskRelationMapper.deleteRelation(processTaskRelationLog);
+        if (0 == deleteRelation) {
+            putMsg(result, Status.DELETE_TASK_PROCESS_RELATION_ERROR);
+        }
+
+        TaskDefinition taskDefinition = taskDefinitionMapper.queryByCode(taskCode);
+        if (null == taskDefinition) {
+            putMsg(result, Status.DATA_IS_NULL, "taskDefinition");
+            return result;
+        }
+        if (TaskType.CONDITIONS.getDesc().equals(taskDefinition.getTaskType())
+                || TaskType.DEPENDENT.getDesc().equals(taskDefinition.getTaskType())
+                || TaskType.SUB_PROCESS.getDesc().equals(taskDefinition.getTaskType())) {
+            int deleteTaskDefinition = taskDefinitionMapper.deleteByCode(taskCode);
+            if (0 == deleteTaskDefinition) {
+                putMsg(result, Status.DELETE_TASK_PROCESS_RELATION_ERROR);
+            }
+        }
+        return result;
     }
 
     /**
diff --git a/dolphinscheduler-api/src/test/java/org/apache/dolphinscheduler/api/service/ProcessTaskRelationServiceTest.java b/dolphinscheduler-api/src/test/java/org/apache/dolphinscheduler/api/service/ProcessTaskRelationServiceTest.java
index 55efbfe088c9b3961452a76088d1646a42b0ce80..2b7b5a7fe9f70d869d47dd1cf19afe989b0652b3 100644
--- a/dolphinscheduler-api/src/test/java/org/apache/dolphinscheduler/api/service/ProcessTaskRelationServiceTest.java
+++ b/dolphinscheduler-api/src/test/java/org/apache/dolphinscheduler/api/service/ProcessTaskRelationServiceTest.java
@@ -21,6 +21,7 @@ import org.apache.dolphinscheduler.api.enums.Status;
 import org.apache.dolphinscheduler.api.service.impl.ProcessTaskRelationServiceImpl;
 import org.apache.dolphinscheduler.api.service.impl.ProjectServiceImpl;
 import org.apache.dolphinscheduler.common.Constants;
+import org.apache.dolphinscheduler.common.enums.TaskType;
 import org.apache.dolphinscheduler.common.enums.UserType;
 import org.apache.dolphinscheduler.dao.entity.ProcessDefinition;
 import org.apache.dolphinscheduler.dao.entity.ProcessTaskRelation;
@@ -461,4 +462,34 @@ public class ProcessTaskRelationServiceTest {
         Map<String, Object> result1 = processTaskRelationService.deleteUpstreamRelation(loginUser, projectCode, "123", taskCode);
         Assert.assertEquals(Status.SUCCESS, result1.get(Constants.STATUS));
     }
+
+    @Test
+    public void testDeleteTaskProcessRelation() {
+        long projectCode = 1L;
+        long taskCode = 2L;
+        long processDefinitionCode = 3L;
+        long preTaskCode = 4L;
+        long postTaskCode = 5L;
+        Project project = getProject(projectCode);
+        Mockito.when(projectMapper.queryByCode(projectCode)).thenReturn(project);
+
+        User loginUser = new User();
+        loginUser.setId(-1);
+        loginUser.setUserType(UserType.GENERAL_USER);
+        Map<String, Object> result = new HashMap<>();
+        putMsg(result, Status.SUCCESS, projectCode);
+        Mockito.when(projectService.checkProjectAndAuth(loginUser, project, projectCode)).thenReturn(result);
+        Mockito.when(processTaskRelationMapper.queryByCode(projectCode, processDefinitionCode, preTaskCode, postTaskCode)).thenReturn(Lists.newArrayList());
+        ProcessTaskRelationLog processTaskRelationLog = new ProcessTaskRelationLog();
+        processTaskRelationLog.setProjectCode(projectCode);
+        processTaskRelationLog.setPreTaskCode(taskCode);
+        processTaskRelationLog.setProcessDefinitionCode(processDefinitionCode);
+        Mockito.when(processTaskRelationMapper.deleteRelation(processTaskRelationLog)).thenReturn(1);
+        TaskDefinition taskDefinition = new TaskDefinition();
+        taskDefinition.setTaskType(TaskType.CONDITIONS.getDesc());
+        Mockito.when(taskDefinitionMapper.queryByCode(taskCode)).thenReturn(taskDefinition);
+        Mockito.when(taskDefinitionMapper.deleteByCode(taskCode)).thenReturn(1);
+        result = processTaskRelationService.deleteTaskProcessRelation(loginUser, projectCode, processDefinitionCode, taskCode);
+        Assert.assertEquals(Status.SUCCESS, result.get(Constants.STATUS));
+    }
 }