In order to solve the problem that the opening and closing speed of traditional hydraulic control gate valve cannot be adjusted,easy to cause waterhammer,and cannot cope with the sudden power failure,a stepless electromechanical hydraulic combined control drainage gate valve was designed.The mechanical structure and hydraulic system design scheme of the gate valve were proposed,and the electromechanical hydraulic co-simulation model of the gate valve was established to optimize the key parameters affecting the performance of the gate valve.The results show that:when the opening pressure of the hydraulic control check valve is set at 0.8 MPa,the opening valve throttle valve aperture is set at 1.4 mm,and the closing valve throttle valve aperture is set at 1.2 mm,the stable operation of the gate valve can be realized without affecting the drainage efficiency.Finally,the feasibility of the design scheme of the gate valve and the rationality of the parameter selection are verified by experimental prototype.It provides reference for the further development and application of this kind of gate valve.