A method of combining fuzzy Petri net theory with expert system is applied to diagnose faults in power consumption information acquisition system, and the efficiency of fault diagnosis of power consumption information acquisition system is improved. According to the fault logic relationship of power consumption information acquisition system, combined with the Petri net modeling method, the fuzzy fault Petri net model is established. Through the reverse reasoning method, the accurate assessment of the system operating status is realized. Finally, the inference process of fault diagnosis is verified with an example. This proves the reliability and rationality of the method.