Aiming at the problem during the fusion process of virtual instrument with simulation system in single thread under Win32 console, put forward a virtual instrument design method based on thread-message mapping mechanism. In this method, the main control program is running under primary thread, and each virtual instrument (including virtual panel) is running under every associate thread. By the thread-message mapping mechanism, the method implements the fusion and cooperation of primary thread with each associate thread running virtual instrument. The practice shows that the method can greatly promote the modularizing efficiency, the interoperability of simulation and the reusability of model in simulation system.