Aiming at the problem of certain type missile borne secondary power source fault diagnosis, use fuzzy Petri net to carry out modeling verification. Based on the traditional fuzzy Petri net, by introducing the transition probability information, the rules of fuzzy production and matrix-based inference calculation are expounded and the models are validated. The results show that the fuzzy probability Petri network has strong applicability and the matrix-based inference operation is clear and efficient, which makes it is easy to diagnose the expansion and maintenance of the model base.