The invention discloses a reusable timing method for parallel time limit reasoning of a real-time expert system. The method comprises the following steps that when a real-time expert system is started, a basic timer gTimer, a timing event queue Q, a timing event management thread tEventManager and a message queue msgQEvent for transmitting messages to the timing event management thread tEventManager are created; a timing event, a timing event queue Q and data items of nodes of the timing event queue Q are defined; whenever the time limit reasoning in any rule in the real-time expert system isstarted, the real-time expert system starts a timing event Ei, and sends the timing event Ei to the timing event management thread tEventManager through the message queue msgQEvent, and inserts the timing event Ei into the timing event queue Q after the timing event management thread tEventManager receives the processing request. The method provided by the invention effectively manages and allocates timer resources for a real-time expert system.