After the wind turbine is connected to the fixed displacement pump,the aerodynamic torque fluctuation has an obvious influence on the grid-connected speed of the regulating unit,which will cause the decrease of the reliability of the transmission chain of the unit.Based on wind speed prediction and aerodynamic torque performance,a control scheme for grid-connected speed of hydraulic motor generator was designed to control the stable grid connection and reduce the load of transmission chain of the unit.Simulink software was used to build a test model of grid-connected speed regulation of vertical shaft hydraulic unit.Then,the variable motor speed regulation effects were verified under the three states of fixed,step and natural fluctuating wind speed.The grid-connected speed tests at steady wind speed and random wind speed show that the pressure fluctuation amplitude of the system can reach 0.1 MPa by using proportional throttle valve and variable motor,which can significantly reduce the high frequency fluctuation of variable motor speed and meet the requirements of grid-connected speed control of wind turbines.