Combining topdown and bottomup design methods,the electrohydraulic servo valve for driving the engine air channel to open was researched.Through simulation experiment platform,the electrohydraulic servo valve under various working conditions was tested respectively,such as no load and dynamic load.The response characteristics of the cam mechanism showed that:the influence factors on the properties of the electrohydraulic servo valve were the spring and the valve bush.By using replacement method,the properties of the electrohydraulic servo valve,in which the spring and the valve bush were replaced,was tested.Based on the sampling data analysis,the defects in the design were found.This study is useful for improving the properties of the electrohydraulic servo valve.