The invention discloses a method and a device for realizing thread local storage. In the method, a global variable is converted into a thread local storage variable of a task to realize the thread local storage. The method comprises the following steps of: the global variable in a source code is revised into a global pointer; in a task switching callback function of an operating system, a global pointer address switching operation is added; the task local storage space of the thread local storage is distributed to the global variable; and through the global pointer, access to the thread local storage variable is finished. According to the method and the device, the global variable is converted into the TLS (Thread Local Storage) of the task to realize the TLS. By use of the method, no processors or compilers are required to provide a special support, the original operating system is not revised, the method and the device are high in application flexibility, the implementation difficulty of the TLS is greatly lowered, and the application range of the TLS is expanded.