diff --git a/components/drivers/ipc/waitqueue.c b/components/drivers/ipc/waitqueue.c
index 7847c6dde2cd85f203d5f363183035fce9f5da32..7bf40d3add56b2d3ee626f6dd27c94cc11443627 100644
--- a/components/drivers/ipc/waitqueue.c
+++ b/components/drivers/ipc/waitqueue.c
@@ -75,7 +75,7 @@ int __wqueue_default_wake(struct rt_wqueue_node *wait, void *key)
 void rt_wqueue_wakeup(rt_wqueue_t *queue, void *key)
 {
     rt_base_t level;
-    register int need_schedule = 0;
+    int need_schedule = 0;
 
     rt_list_t *queue_list;
     struct rt_list_node *node;
diff --git a/components/libc/compilers/common/time.c b/components/libc/compilers/common/time.c
index 9290645789f4d28fc28f5a210894059dd0e5a90a..8deccbba2c775b807ffcc02d757d9608b6b05423 100644
--- a/components/libc/compilers/common/time.c
+++ b/components/libc/compilers/common/time.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2006-2021, RT-Thread Development Team
+ * Copyright (c) 2006-2022, RT-Thread Development Team
  *
  * SPDX-License-Identifier: Apache-2.0
  *
@@ -172,7 +172,7 @@ static int set_timeval(struct timeval *tv)
 struct tm *gmtime_r(const time_t *timep, struct tm *r)
 {
     time_t i;
-    register time_t work = *timep % (SPD);
+    time_t work = *timep % (SPD);
     r->tm_sec = work % 60;
     work /= 60;
     r->tm_min = work % 60;
@@ -181,7 +181,7 @@ struct tm *gmtime_r(const time_t *timep, struct tm *r)
     r->tm_wday = (4 + work) % 7;
     for (i = 1970;; ++i)
     {
-        register time_t k = __isleap(i) ? 366 : 365;
+        time_t k = __isleap(i) ? 366 : 365;
         if (work >= k)
             work -= k;
         else
@@ -367,9 +367,9 @@ RTM_EXPORT(stime);
 
 time_t timegm(struct tm * const t)
 {
-    register time_t day;
-    register time_t i;
-    register time_t years = (time_t)t->tm_year - 70;
+    time_t day;
+    time_t i;
+    time_t years = (time_t)t->tm_year - 70;
 
     if (t->tm_sec > 60)         /* seconds after the minute - [0, 60] including leap second */
     {
diff --git a/src/idle.c b/src/idle.c
index ea8eb61c46e51a4b774e432ab971096e720966b6..4d147a297a3ce860cb68588f22b734c52fa5834f 100644
--- a/src/idle.c
+++ b/src/idle.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2006-2021, RT-Thread Development Team
+ * Copyright (c) 2006-2022, RT-Thread Development Team
  *
  * SPDX-License-Identifier: Apache-2.0
  *
@@ -344,9 +344,9 @@ void rt_thread_idle_init(void)
 rt_thread_t rt_thread_idle_gethandler(void)
 {
 #ifdef RT_USING_SMP
-    register int id = rt_hw_cpu_id();
+    int id = rt_hw_cpu_id();
 #else
-    register int id = 0;
+    int id = 0;
 #endif /* RT_USING_SMP */
 
     return (rt_thread_t)(&idle[id]);
diff --git a/src/ipc.c b/src/ipc.c
index 912ff81536a8bb22a04d66f0c386bc53c2635e30..4a6244ac3b4ae053b1bc7783aacbeda451d2443c 100644
--- a/src/ipc.c
+++ b/src/ipc.c
@@ -606,7 +606,7 @@ RTM_EXPORT(rt_sem_trytake);
 rt_err_t rt_sem_release(rt_sem_t sem)
 {
     rt_base_t level;
-    register rt_bool_t need_schedule;
+    rt_bool_t need_schedule;
 
     /* parameter check */
     RT_ASSERT(sem != RT_NULL);
@@ -1442,7 +1442,7 @@ rt_err_t rt_event_send(rt_event_t event, rt_uint32_t set)
     struct rt_list_node *n;
     struct rt_thread *thread;
     rt_base_t level;
-    register rt_base_t status;
+    rt_base_t status;
     rt_bool_t need_schedule;
 
     /* parameter check */
@@ -1570,7 +1570,7 @@ rt_err_t rt_event_recv(rt_event_t   event,
 {
     struct rt_thread *thread;
     rt_base_t level;
-    register rt_base_t status;
+    rt_base_t status;
 
     /* parameter check */
     RT_ASSERT(event != RT_NULL);
@@ -2491,7 +2491,7 @@ rt_err_t rt_mq_init(rt_mq_t     mq,
                     rt_uint8_t  flag)
 {
     struct rt_mq_message *head;
-    register rt_base_t temp;
+    rt_base_t temp;
 
     /* parameter check */
     RT_ASSERT(mq != RT_NULL);
@@ -2615,7 +2615,7 @@ rt_mq_t rt_mq_create(const char *name,
 {
     struct rt_messagequeue *mq;
     struct rt_mq_message *head;
-    register rt_base_t temp;
+    rt_base_t temp;
 
     RT_ASSERT((flag == RT_IPC_FLAG_FIFO) || (flag == RT_IPC_FLAG_PRIO));
 
diff --git a/src/kservice.c b/src/kservice.c
index ff9d3c9cef401b2287f9290a9177411f3973bd8d..f1df8a179d2fb8863e1b49b3383057d500bbe470 100644
--- a/src/kservice.c
+++ b/src/kservice.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2006-2021, RT-Thread Development Team
+ * Copyright (c) 2006-2022, RT-Thread Development Team
  *
  * SPDX-License-Identifier: Apache-2.0
  *
@@ -495,7 +495,7 @@ RTM_EXPORT(rt_strcpy);
  */
 rt_int32_t rt_strncmp(const char *cs, const char *ct, rt_size_t count)
 {
-    register signed char __res = 0;
+    signed char __res = 0;
 
     while (count)
     {
@@ -668,7 +668,7 @@ rt_inline int divide(long *n, int base)
 
 rt_inline int skip_atoi(const char **s)
 {
-    register int i = 0;
+    int i = 0;
     while (_ISDIGIT(**s))
         i = i * 10 + *((*s)++) - '0';
 
@@ -707,8 +707,7 @@ static char *print_number(char *buf,
     const char *digits;
     static const char small_digits[] = "0123456789abcdef";
     static const char large_digits[] = "0123456789ABCDEF";
-    register int i;
-    register int size;
+    int i, size;
 
     size = s;
 
diff --git a/src/mempool.c b/src/mempool.c
index 44010bbace7398f877b3baf91e28112d83f181f8..197c8af488c5af9eebd242d028a5a61ec1a30607 100644
--- a/src/mempool.c
+++ b/src/mempool.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2006-2021, RT-Thread Development Team
+ * Copyright (c) 2006-2022, RT-Thread Development Team
  *
  * SPDX-License-Identifier: Apache-2.0
  *
@@ -93,7 +93,7 @@ rt_err_t rt_mp_init(struct rt_mempool *mp,
                     rt_size_t          block_size)
 {
     rt_uint8_t *block_ptr;
-    register rt_size_t offset;
+    rt_size_t offset;
 
     /* parameter check */
     RT_ASSERT(mp != RT_NULL);
@@ -201,7 +201,7 @@ rt_mp_t rt_mp_create(const char *name,
 {
     rt_uint8_t *block_ptr;
     struct rt_mempool *mp;
-    register rt_size_t offset;
+    rt_size_t offset;
 
     RT_DEBUG_NOT_IN_INTERRUPT;
 
diff --git a/src/scheduler.c b/src/scheduler.c
index a6729b9b09efcfceaac292b179babb2f09ed6a31..9571cd8ca74b73f29fb91e9b7d95e37bfd1d2527 100644
--- a/src/scheduler.c
+++ b/src/scheduler.c
@@ -132,11 +132,11 @@ static void _rt_scheduler_stack_check(struct rt_thread *thread)
 #ifdef RT_USING_SMP
 static struct rt_thread* _scheduler_get_highest_priority_thread(rt_ubase_t *highest_prio)
 {
-    register struct rt_thread *highest_priority_thread;
-    register rt_ubase_t highest_ready_priority, local_highest_ready_priority;
+    struct rt_thread *highest_priority_thread;
+    rt_ubase_t highest_ready_priority, local_highest_ready_priority;
     struct rt_cpu* pcpu = rt_cpu_self();
 #if RT_THREAD_PRIORITY_MAX > 32
-    register rt_ubase_t number;
+    rt_ubase_t number;
 
     number = __rt_ffs(rt_thread_ready_priority_group) - 1;
     highest_ready_priority = (number << 3) + __rt_ffs(rt_thread_ready_table[number]) - 1;
@@ -168,11 +168,11 @@ static struct rt_thread* _scheduler_get_highest_priority_thread(rt_ubase_t *high
 #else
 static struct rt_thread* _scheduler_get_highest_priority_thread(rt_ubase_t *highest_prio)
 {
-    register struct rt_thread *highest_priority_thread;
-    register rt_ubase_t highest_ready_priority;
+    struct rt_thread *highest_priority_thread;
+    rt_ubase_t highest_ready_priority;
 
 #if RT_THREAD_PRIORITY_MAX > 32
-    register rt_ubase_t number;
+    rt_ubase_t number;
 
     number = __rt_ffs(rt_thread_ready_priority_group) - 1;
     highest_ready_priority = (number << 3) + __rt_ffs(rt_thread_ready_table[number]) - 1;
@@ -199,7 +199,7 @@ void rt_system_scheduler_init(void)
 #ifdef RT_USING_SMP
     int cpu;
 #endif /* RT_USING_SMP */
-    register rt_base_t offset;
+    rt_base_t offset;
 
 #ifndef RT_USING_SMP
     rt_scheduler_lock_nest = 0;
@@ -247,7 +247,7 @@ void rt_system_scheduler_init(void)
  */
 void rt_system_scheduler_start(void)
 {
-    register struct rt_thread *to_thread;
+    struct rt_thread *to_thread;
     rt_ubase_t highest_ready_priority;
 
     to_thread = _scheduler_get_highest_priority_thread(&highest_ready_priority);
@@ -870,7 +870,7 @@ void rt_enter_critical(void)
      */
 
     {
-        register rt_uint16_t lock_nest = current_thread->cpus_lock_nest;
+        rt_uint16_t lock_nest = current_thread->cpus_lock_nest;
         current_thread->cpus_lock_nest++;
         if (lock_nest == 0)
         {
diff --git a/src/thread.c b/src/thread.c
index 45107ced3c957af98d51a1b58ef38f019d78ff4e..7bd4ea6e33d043163a748304ad1ce34c7ab645f6 100755
--- a/src/thread.c
+++ b/src/thread.c
@@ -327,7 +327,7 @@ RTM_EXPORT(rt_thread_init);
 rt_thread_t rt_thread_self(void)
 {
 #ifdef RT_USING_SMP
-    register rt_base_t lock;
+    rt_base_t lock;
     rt_thread_t self;
 
     lock = rt_hw_local_irq_disable();
@@ -836,7 +836,7 @@ RTM_EXPORT(rt_thread_control);
  */
 rt_err_t rt_thread_suspend(rt_thread_t thread)
 {
-    register rt_base_t stat;
+    rt_base_t stat;
     rt_base_t level;
 
     /* parameter check */
diff --git a/src/timer.c b/src/timer.c
index f72c71ab9bad502d1305f3f97e15fb091ff32a1f..0600f85694dc7bf33ab6f9bb6a885f2251c1f9ed 100644
--- a/src/timer.c
+++ b/src/timer.c
@@ -409,7 +409,7 @@ rt_err_t rt_timer_start(rt_timer_t timer)
     unsigned int row_lvl;
     rt_list_t *timer_list;
     rt_base_t level;
-    register rt_bool_t need_schedule;
+    rt_bool_t need_schedule;
     rt_list_t *row_head[RT_TIMER_SKIP_LIST_LEVEL];
     unsigned int tst_nr;
     static unsigned int random_nr;