diff --git a/src/clock.c b/src/clock.c
index 7df13775b2..77516b3775 100644
--- a/src/clock.c
+++ b/src/clock.c
@@ -24,7 +24,7 @@
 #define rt_tick rt_cpu_index(0)->tick
 #else
 static volatile rt_tick_t rt_tick = 0;
-#endif
+#endif /* RT_USING_SMP */
 
 /**
  * @addtogroup Clock
@@ -72,7 +72,7 @@ void rt_tick_increase(void)
     rt_cpu_self()->tick ++;
 #else
     ++ rt_tick;
-#endif
+#endif /* RT_USING_SMP */
 
     /* check time slice */
     thread = rt_thread_self();
@@ -138,7 +138,7 @@ RT_WEAK rt_tick_t rt_tick_get_millisecond(void)
     #warning "rt-thread cannot provide a correct 1ms-based tick any longer,\
     please redefine this function in another file by using a high-precision hard-timer."
     return 0;
-#endif
+#endif /* 1000 % RT_TICK_PER_SECOND == 0u */
 }
 
 /**@}*/
diff --git a/src/components.c b/src/components.c
index 9709d0aae2..d684d5e6fd 100644
--- a/src/components.c
+++ b/src/components.c
@@ -23,11 +23,11 @@
 #ifdef RT_USING_USER_MAIN
 #ifndef RT_MAIN_THREAD_STACK_SIZE
 #define RT_MAIN_THREAD_STACK_SIZE     2048
-#endif
+#endif /* RT_MAIN_THREAD_STACK_SIZE */
 #ifndef RT_MAIN_THREAD_PRIORITY
 #define RT_MAIN_THREAD_PRIORITY       (RT_THREAD_PRIORITY_MAX / 3)
-#endif
-#endif
+#endif /* RT_MAIN_THREAD_PRIORITY */
+#endif /* RT_USING_USER_MAIN */
 
 #ifdef RT_USING_COMPONENTS_INIT
 /*
@@ -98,7 +98,7 @@ void rt_components_board_init(void)
     {
         (*fn_ptr)();
     }
-#endif
+#endif /* RT_DEBUG_INIT */
 }
 
 /**
@@ -124,9 +124,9 @@ void rt_components_init(void)
     {
         (*fn_ptr)();
     }
-#endif
+#endif /* RT_DEBUG_INIT */
 }
-#endif   /* RT_USING_COMPONENTS_INIT */
+#endif /* RT_USING_COMPONENTS_INIT */
 
 #ifdef RT_USING_USER_MAIN
 
@@ -167,7 +167,7 @@ int entry(void)
 ALIGN(8)
 static rt_uint8_t main_stack[RT_MAIN_THREAD_STACK_SIZE];
 struct rt_thread main_thread;
-#endif
+#endif /* RT_USING_HEAP */
 
 /* the system main thread */
 void main_thread_entry(void *parameter)
@@ -177,11 +177,11 @@ void main_thread_entry(void *parameter)
 #ifdef RT_USING_COMPONENTS_INIT
     /* RT-Thread components initialization */
     rt_components_init();
-#endif
+#endif /* RT_USING_COMPONENTS_INIT */
 
 #ifdef RT_USING_SMP
     rt_hw_secondary_cpu_up();
-#endif
+#endif /* RT_USING_SMP */
     /* invoke system main function */
 #if defined(__CC_ARM) || defined(__CLANG_ARM)
     {
@@ -211,7 +211,7 @@ void rt_application_init(void)
 
     /* if not define RT_USING_HEAP, using to eliminate the warning */
     (void)result;
-#endif
+#endif /* RT_USING_HEAP */
 
     rt_thread_startup(tid);
 }
@@ -237,7 +237,7 @@ int rtthread_startup(void)
 #ifdef RT_USING_SIGNALS
     /* signal system initialization */
     rt_system_signal_init();
-#endif
+#endif /* RT_USING_SIGNALS */
 
     /* create init_thread */
     rt_application_init();
@@ -250,7 +250,7 @@ int rtthread_startup(void)
 
 #ifdef RT_USING_SMP
     rt_hw_spin_lock(&_cpus_lock);
-#endif /*RT_USING_SMP*/
+#endif /* RT_USING_SMP */
 
     /* start scheduler */
     rt_system_scheduler_start();
@@ -258,4 +258,4 @@ int rtthread_startup(void)
     /* never reach here */
     return 0;
 }
-#endif
+#endif /* RT_USING_USER_MAIN */
diff --git a/src/cpu.c b/src/cpu.c
index 48ddb12c46..a7d56ba999 100644
--- a/src/cpu.c
+++ b/src/cpu.c
@@ -185,4 +185,4 @@ void rt_cpus_lock_status_restore(struct rt_thread *thread)
 }
 RTM_EXPORT(rt_cpus_lock_status_restore);
 
-#endif
+#endif /* RT_USING_SMP */
diff --git a/src/device.c b/src/device.c
index 50b83c7692..a9c244d306 100644
--- a/src/device.c
+++ b/src/device.c
@@ -16,9 +16,9 @@
  */
 
 #include <rtthread.h>
-#if defined(RT_USING_POSIX)
+#ifdef RT_USING_POSIX
 #include <rtdevice.h> /* for wqueue_init */
-#endif
+#endif /* RT_USING_POSIX */
 
 #ifdef RT_USING_DEVICE
 
@@ -36,7 +36,7 @@
 #define device_read     (dev->read)
 #define device_write    (dev->write)
 #define device_control  (dev->control)
-#endif
+#endif /* RT_USING_DEVICE_OPS */
 
 /**
  * This function registers a device driver with specified name.
@@ -62,10 +62,10 @@ rt_err_t rt_device_register(rt_device_t dev,
     dev->ref_count = 0;
     dev->open_flag = 0;
 
-#if defined(RT_USING_POSIX)
+#ifdef RT_USING_POSIX
     dev->fops = RT_NULL;
     rt_wqueue_init(&(dev->wait_queue));
-#endif
+#endif /* RT_USING_POSIX */
 
     return RT_EOK;
 }
@@ -150,7 +150,7 @@ void rt_device_destroy(rt_device_t dev)
     rt_free(dev);
 }
 RTM_EXPORT(rt_device_destroy);
-#endif
+#endif /* RT_USING_HEAP */
 
 /**
  * This function will initialize the specified device
@@ -434,4 +434,4 @@ rt_device_set_tx_complete(rt_device_t dev,
 }
 RTM_EXPORT(rt_device_set_tx_complete);
 
-#endif
+#endif /* RT_USING_DEVICE */
diff --git a/src/idle.c b/src/idle.c
index e73a78be9c..db256a6010 100644
--- a/src/idle.c
+++ b/src/idle.c
@@ -22,27 +22,27 @@
 
 #ifdef RT_USING_MODULE
 #include <dlmodule.h>
-#endif
+#endif /* RT_USING_MODULE */
 
-#if defined (RT_USING_HOOK)
+#ifdef RT_USING_HOOK
 #ifndef RT_USING_IDLE_HOOK
 #define RT_USING_IDLE_HOOK
-#endif
-#endif
+#endif /* RT_USING_IDLE_HOOK */
+#endif /* RT_USING_HOOK */
 
 #ifndef IDLE_THREAD_STACK_SIZE
 #if defined (RT_USING_IDLE_HOOK) || defined(RT_USING_HEAP)
 #define IDLE_THREAD_STACK_SIZE  256
 #else
 #define IDLE_THREAD_STACK_SIZE  128
-#endif
-#endif
+#endif /* (RT_USING_IDLE_HOOK) || defined(RT_USING_HEAP) */
+#endif /* IDLE_THREAD_STACK_SIZE */
 
 #ifdef RT_USING_SMP
 #define _CPUS_NR                RT_CPUS_NR
 #else
 #define _CPUS_NR                1
-#endif
+#endif /* RT_USING_SMP */
 
 extern rt_list_t rt_thread_defunct;
 
@@ -53,7 +53,7 @@ static rt_uint8_t rt_thread_stack[_CPUS_NR][IDLE_THREAD_STACK_SIZE];
 #ifdef RT_USING_IDLE_HOOK
 #ifndef RT_IDLE_HOOK_LIST_SIZE
 #define RT_IDLE_HOOK_LIST_SIZE  4
-#endif
+#endif /* RT_IDLE_HOOK_LIST_SIZE */
 
 static void (*idle_hook_list[RT_IDLE_HOOK_LIST_SIZE])(void);
 
@@ -125,7 +125,7 @@ rt_err_t rt_thread_idle_delhook(void (*hook)(void))
     return ret;
 }
 
-#endif
+#endif /* RT_USING_IDLE_HOOK */
 
 #ifdef RT_USING_HEAP
 /* Return whether there is defunctional thread to be deleted. */
@@ -141,7 +141,7 @@ rt_inline int _has_defunct_thread(void)
 
     return l->next != l;
 }
-#endif
+#endif /* RT_USING_HEAP */
 
 /**
  * @ingroup Thread
@@ -182,7 +182,7 @@ void rt_thread_idle_excute(void)
         rt_object_delete((rt_object_t)thread);
         rt_hw_interrupt_enable(lock);
     }
-#endif
+#endif /* RT_USING_HEAP */
 }
 
 extern void rt_system_power_manager(void);
@@ -196,7 +196,7 @@ static void rt_thread_idle_entry(void *parameter)
             rt_hw_secondary_cpu_idle_exec();
         }
     }
-#endif
+#endif /* RT_USING_SMP */
 
     while (1)
     {
@@ -212,12 +212,12 @@ static void rt_thread_idle_entry(void *parameter)
                 idle_hook();
             }
         }
-#endif
+#endif /* RT_USING_IDLE_HOOK */
 
         rt_thread_idle_excute();
 #ifdef RT_USING_PM
         rt_system_power_manager();
-#endif
+#endif /* RT_USING_PM */
     }
 }
 
@@ -246,7 +246,7 @@ void rt_thread_idle_init(void)
                 32);
 #ifdef RT_USING_SMP
         rt_thread_control(&idle[i], RT_THREAD_CTRL_BIND_CPU, (void*)i);
-#endif
+#endif /* RT_USING_SMP */
         /* startup */
         rt_thread_startup(&idle[i]);
     }
@@ -264,7 +264,7 @@ rt_thread_t rt_thread_idle_gethandler(void)
     register int id = rt_hw_cpu_id();
 #else
     register int id = 0;
-#endif
+#endif /* RT_USING_SMP */
 
     return (rt_thread_t)(&idle[id]);
 }