Aiming at the power control of VSCF wind turbine,the design scheme of the hydraulic variable pitch system based on electro hydraulic proportional valve was proposed,scheme design of hydraulic system,design calculation and selection of hydraulic components for hydraulic system were discussed in details,and the designed system was simulated by FluidSIM 5 Hydraulics software platform.The simulation results verify the correctness and feasibility of the design of the hydraulic variable pitch system,and the rationality of the simulation model.The hydraulic variable pitch system can meet the variable pitch wind turbine pitch angle control for fast and accurate requirements.It lays foundation for optimization design of variable pitch hydraulic system of variable speed constant frequency wind turbine.