As　the　global　energy　and　environmental　situation　is　serious,　the　wind　energy　as　a　clean,　renewable　energy,　is　got　more　and　more　world　attention.　Wind　power　technology　is　becoming　the　research　focus　of　many　countries.　Hydraulic　system　with　its　high　reliability　and　fast　response　characters　is　widely　used　in　the　rotor　brake　system,　yaw　brake　system,　pitch　system.