A fixing device of a motor front end cover used for a valve is disclosed. The invention relates to a valve electric actuator, and particularly relates to design and fixation of the motor front end cover used for the valve. The invention provides the fixing device of the motor front end cover used for the valve which has the characteristics of compact structure and simplicity, safety and reliability. One end of a shell body is provided with an opening, and a stator and a rotor are disposed inside the shell body; The fixing device is characterized in that the fixing device also includes at leasttwo pressing plates; the opening of the shell body is used for connecting a front end cover; a ring groove is disposed on the opening; the front end cover is located inside the ring groove, and the pressing plates are located in the ring groove; and the pressing plates are provided with through holes, the front end cover is provided with threaded holes, and the through holes correspond to the threaded holes and are connected with countersunk screws. An O-shaped ring groove is disposed around the front end cover, an O-shaped seal ring is disposed in the O-shaped ring groove, and the O-shaped seal ring is used for contacting the inner wall of the shell body. The fixing device is reasonable in design and is safe and reliable.