The main parameters of the hydro servo cylinder were defined by calculation,guide strip series sealing ring was designed to support the piston weight, meeting high pressure sealing requirements with low friction. A pair of washers with small helical angle was used to solve problems caused by screw clearance under dynamic force. Based on flow demand of the servo cylinder, a pilot controlled parallel servo valve hydraulic system was designed. The test results show that designed servo cylinder system can meet vibration test requirements for large size damper.