In traditional test system, the evaluation of the performance of the missile control system is too rough and inaccurate, thus it is proposed to use the membership function to refine the performance status level.By using the improved D-S evidence theory, the problem of mistakes arisen when fusing the high-conflict evidences is solved, comprehensive analysis is made to the dynamic and static data of the closed-loop simulated test of the control system, and the performance status levels of the key nodes and the whole process during the simulated flight are obtained, according to which the test and maintenance cycle can be adjusted.The simulation verifies the feasibility of the method.