The invention discloses a power system fault automatic diagnosis method based on a fuzzy reasoning spiking neural P system. Firstly, topological data representing the whole topological structure of apower network, and protection data of protection configuration of a power grid network, are constructed. Secondly, after a SCADA system provides action information of protection and switching, a powernetwork topology analysis algorithm program is called to determine related suspicious fault elements based on on-off states of a breaker, a fuzzy reasoning spiking neural P system diagnosis model corresponding to each suspicious fault element is generated, and then, a reasoning algorithm of the fuzzy reasoning spiking neural P system is called to determine the fault elements. In the method provided by the invention, fault diagnosis of the fuzzy reasoning spiking neural P system in a power transmission network is realized through a programmed mode. The whole fault diagnosis process is realizedautomatically, even under a situation of complex faults of a large-scale power network and a situation where the SCADA system provides complete fault information or information, such as information of maloperation or failure to operate of a protection breaker, is not complete, correct diagnosis results can be obtained efficiently and automatically.