Fault tolerance is a basic requirement of the multi-sensor integrated navigation system.In order to improve the ability of the integrated navigation system to detect abrupt and gradual faults, a fault-tolerant algorithm combining principal component analysis with integrated navigation is designed.The theory of multi-sensor integrated navigation system is introduced in detail, and the fault detection and identification based on principal component analysis are introduced in detail.The fault tolerance performance of the integrated navigation system is analyzed.The experimental results show that the fault-tolerant algorithm which combines principal component analysis with integrated navigation has good detection ability for both the abrupt and gradual faults of the navigation sensor, and the fault-tolerant performance of the navigation system is obviously improved.