With the development of power industry, communication security has become an important issue affecting the stability of power system. IEC 62351 standard provides security for substation communication system. However, different transmission protocols may lead to different manufacturers to produce different understanding, manufacturing is not compatible with the device. In order to avoid such a situation, the Finite State Machine (FSM) theory is used to model and analyze the transmission protocol of IEC 62351 standard. In this paper, the FSM model is simulated by the StateFlow tool, and it can be considered that the FSM theory is applicable to the analysis of compliance with IEC 62351 standard.