In order to test the functions and performance parameters of a new type of aircraft combined servo actuator, a servo actuator measuring system was designed. In the measuring system, hydraulic spring was adopted to load, and the system was controlled by computer automatically. It could simulate the working environment of servo actuator by which the servo valve, LVDT and all accessories of the combined servo actuator could be tested. And maintenance guiding module of malfunction expert was integrated in the system which could guide to solve problems occurred when testing. The experimental results show that it can effectively shorten the testing time, improve the test efficiency and detection precision, also reduce the test cost.