/***************************************************************************** 
* 
* File Name :  main. c
* 
* Description:  main 
* 
* Copyright  (c)  2014 Winner Micro Electronic Design Co. ,  Ltd.  
* All rights reserved.  
* 
* Author :  dave
* 
* Date :  2014-6-14
*****************************************************************************/ 
#include "wm_include. h"
static OS_STK TaskStk1[512]; 
static OS_STK TaskStk2[512]; 
static void user_task1 (void) 
{
    while (1) 
    {
        printf ("---"  %s\r\n", __func__) ; 
        tls_os_time_delay (HZ) ; 
    }
}
static void user_task2 (void) 
{
    while (1) 
    {
        printf ("---"  %s\r\n", __func__) ; 
        tls_os_time_delay (HZ) ; 
    }
}
void UserMain (void) 
{
    printf ("\n user task \n") ; 
    tls_os_task_create (NULL,  "task1", 
                         ( void  (*) ) user_task1, 
                        NULL, 
                         (void *) TaskStk1,           /* task's stack start address */
                        sizeof (TaskStk1) ,  /* task's stack size,  unit: byte */
                        31, 
                        0) ; 
    tls_os_task_create (NULL,  "task2", 
                         ( void  (*) ) user_task2, 
                        NULL, 
                         (void *) TaskStk2,           /* task's stack start address */
                        sizeof (TaskStk2) ,  /* task's stack size,  unit: byte */
                        32, 
                        0) ; 
#if DEMO_CONSOLE
    CreateDemoTask () ; 
#endif
//用户自己的 task
}

问题已解决, 和任务栈的大小有关,