Abstract: Reliability allocation is an important method to reasonably allocate reliability indexes to each subsystem and ensure the stability of mechanical system. In order to improve the accuracy of reliability allocation, a reliability allocation method of mechanical system based on comprehensive factor fuzzy analytic hierarchy process is proposed in this paper. Firstly, the system hierarchy is established, and the analytic hierarchy process is used to distribute the weight of different influencing factors. Then, the comprehensive factor fuzzy evaluation method is used to conduct fuzzy evaluation and uncertainty information processing on the subsystem, so as to establish a fuzzy relationship matrix, determine the factor combination weight, and obtain the system reliability distribution scheme. Finally, combined with the analysis of industrial robot system, it meets te requirements of reducing the reliability allocation index of reducer and improving the reliability allocation index of robot arm and controller in industrial robot system.