Hydraulic actuator used in compressor capacity regulation system is a hydromechatronics equipment, the high frequency selector valve is the core element of the system. The function of the selector valve is to receive the control instruction signal of PC system, and to realize the onoff control of hydraulic system. Hydraulic oil acts on the hydraulic cylinder piston to press off the inlet valve and unload at a certain time. This is the operating principle of compressor capacity regulation system. The performances of hydraulic actuator were explored with different operation conditions adopting AMESim simulation and experimental methods. The results show that hydraulic actuator performances under different operating conditions has very big differences. Simulation results have good consistency with the experimental results. Simulation method can be effectively applied to the hydraulic actuator performance evaluation.