Aiming at grid-connected speed control of a hydraulic wind turbine with bladder accumulator under the conditions of wind and synchronous generator load changes， a new grid-connected speed control method is proposed—decoupled generalized predictive optimization control （DGPOC）. Firstly， the feedforward decoupling method and generalized prediction are used in DGPOC to remove the coupling relationship between the variable motor swing angle and the accumulator proportional valve lift. The accumulator proportional valve and the variable motor swing angle are adjusted synchronously to achieve constant speed control. Secondly， as a performance constraint， the energy loss of the accumulator proportional valve is introduced into the optimization objective function to improve the wind energy utilization rate. Finally， the simulation results conducted on the MATLAB-AMESim platform validate that the DGPOC can not only improve the speed and robustness of variable motor speed control， but also reduce the energy loss of the system.