The ball screw rated static or dynamic load loading test is necessary process before accepted. With the industrial computer, AC servo motor and hydraulic system with proportional overflow valve as pressure regulating element, a loading test bench for ball screw was constructed. By PID control for proportional overflow valve, the loading hydraulic cylinder could output accurate and stable force in static rated load loading test. Using proportional overflow valve backpressure as the load, with AC servo motor driving the ball screw to run, the running speed was easy to control in dynamic rated load running test and efficiency test. In actual test, the test works reliably and steadily.