Interrelated theories of expert system and artificial neural network are applied to the thorough study of navigation attitude system failure diagnosis problem, and an integrated failure diagnosis expert system is established based on expert system and artificial neural network. By using this integrated failure diagnosis expert system, the failure diagnosis of a navigation attitude system is realized. The result shows that the neural network data error is 0.1 when training 10 times and 0.01when training 829 times which means an accurate identification of failure.