Aiming at the dynamic characteristics of automatic weapons, a real-time monitoring method based on the movement period characteristics of the automata is proposed. For the purpose of fault analysis based on movement patterns, a test system is built to analyze the monitoring reliability of the system's movement period, and the virtual prototype simulation analysis of the tested automatic weapon under a variety of typical faults is carried out to obtain the dynamics parameters and corresponding period characteristics of its automata in the fault state. The test and virtual prototype simulation results show that the monitoring method can accurately and effectively diagnose the typical faults such as automata stagnation, recoil spring failure, extraction fault, etc., and can be used to monitor whether the movement of the firearm is normal or not.