In order to improve the accuracy of fire in tank fire control system, a fault diagnosis expert system for tank fire control system based on fault tree and rule is proposed. According to the characteristics of the system and related professional knowledge to build fault tree, combined with the construction principle of the tank fire control fault diagnosis expert system, reverse reasoning strategy combined with depth first search method is used. The effect of the components on the performance of the tank fire control system is qualitatively and quantitatively analyzed by the fault tree, and the transformation rules of the fault tree are given, and the improved reverse reasoning strategy is obtained. The research results show that this method improves the search efficiency and provides reference for other fire control system fault diagnosis.