diff --git a/docs/zh/api.md b/docs/zh/api.md
index ebc2857..5e46300 100644
--- a/docs/zh/api.md
+++ b/docs/zh/api.md
@@ -52,11 +52,11 @@ char *ef_get_env(const char *key)
 
 #### 1.2.4 设置环境变量
 
-使用此方法可以实现对环境变量的增加、修改功能。（注意：此处的环境变量指代的已加载到内存中的环境变量）
+使用此方法可以实现对环境变量的增加、修改及删除功能。（注意：此处的环境变量指代的已加载到内存中的环境变量）
 
 - **增加** ：当环境变量表中不存在该名称的环境变量时，则会执行新增操作；
-
 - **修改** ：入参中的环境变量名称在当前环境变量表中存在，则把该环境变量值修改为入参中的值；
+- **删除**：当入参中的value为NULL时，则会删除入参名对应的环境变量。 
 
 
 ```C
diff --git a/easyflash/src/ef_env.c b/easyflash/src/ef_env.c
index d2e8f60..a0e0b68 100644
--- a/easyflash/src/ef_env.c
+++ b/easyflash/src/ef_env.c
@@ -478,7 +478,7 @@ static EfErrCode del_env(const char *key) {
 }
 
 /**
- * Set an ENV.
+ * Set an ENV.If it value is NULL, delete it.
  * If not find it in ENV table, then create it.
  *
  * @param key ENV name
@@ -498,22 +498,28 @@ EfErrCode ef_set_env(const char *key, const char *value) {
     /* lock the ENV cache */
     ef_port_env_lock();
 
-    old_env = find_env(key);
-    /* If find this ENV, then compare the new value and old value. */
-    if (old_env) {
-        /* find the old value address */
-        old_env = strchr(old_env, '=');
-        old_value = old_env + 1;
-        /* If it is changed then delete it and recreate it  */
-        if (strcmp(old_value, value)) {
-            result = del_env(key);
-            if (result == EF_NO_ERR) {
-                result = create_env(key, value);
+    /* if ENV value is NULL, delete it */
+    if (value == NULL) {
+        result = del_env(key);
+    } else {
+        old_env = find_env(key);
+        /* If find this ENV, then compare the new value and old value. */
+        if (old_env) {
+            /* find the old value address */
+            old_env = strchr(old_env, '=');
+            old_value = old_env + 1;
+            /* If it is changed then delete it and recreate it  */
+            if (strcmp(old_value, value)) {
+                result = del_env(key);
+                if (result == EF_NO_ERR) {
+                    result = create_env(key, value);
+                }
             }
+        } else {
+            result = create_env(key, value);
         }
-    } else {
-        result = create_env(key, value);
     }
+
     /* unlock the ENV cache */
     ef_port_env_unlock();
 
diff --git a/easyflash/src/ef_env_wl.c b/easyflash/src/ef_env_wl.c
index ef7292f..1cfea0f 100644
--- a/easyflash/src/ef_env_wl.c
+++ b/easyflash/src/ef_env_wl.c
@@ -494,7 +494,7 @@ static EfErrCode del_env(const char *key) {
 }
 
 /**
- * Set an ENV.
+ * Set an ENV.If it value is NULL, delete it.
  * If not find it in ENV table, then create it.
  *
  * @param key ENV name
@@ -514,21 +514,26 @@ EfErrCode ef_set_env(const char *key, const char *value) {
     /* lock the ENV cache */
     ef_port_env_lock();
 
-    old_env = find_env(key);
-    /* If find this ENV, then compare the new value and old value. */
-    if (old_env) {
-        /* find the old value address */
-        old_env = strchr(old_env, '=');
-        old_value = old_env + 1;
-        /* If it is changed then delete it and recreate it  */
-        if (strcmp(old_value, value)) {
-            result = del_env(key);
-            if (result == EF_NO_ERR) {
-                result = create_env(key, value);
+    /* if ENV value is NULL, delete it */
+    if (value == NULL) {
+        result = del_env(key);
+    } else {
+        old_env = find_env(key);
+        /* If find this ENV, then compare the new value and old value. */
+        if (old_env) {
+            /* find the old value address */
+            old_env = strchr(old_env, '=');
+            old_value = old_env + 1;
+            /* If it is changed then delete it and recreate it  */
+            if (strcmp(old_value, value)) {
+                result = del_env(key);
+                if (result == EF_NO_ERR) {
+                    result = create_env(key, value);
+                }
             }
+        } else {
+            result = create_env(key, value);
         }
-    } else {
-        result = create_env(key, value);
     }
     /* unlock the ENV cache */
     ef_port_env_unlock();