Servomotor and hydroelectric power generation system

The utility model provides a servomotor and a hydroelectric power generation system, and the servomotor comprises a telescopic cylinder body which is provided with a telescopic cavity; the piston is mounted in the telescopic chamber and divides the telescopic chamber into a first chamber and a second chamber; the piston rod is mounted in the telescopic cavity, one end of the piston rod is connected with the piston, and the other end extends out of the telescopic cylinder; a first self-sealing ring is installed on the piston, a first self-sealing part extends out of the first self-sealing ring, and part of the first self-sealing part makes contact with the inner wall face of the telescopic cylinder. The pressure of water in the first cavity is applied to the first self-sealing part, so that the first self-sealing part is in full contact with the inner wall surface of the telescopic cylinder and is kept in a sealing state, and the self-sealing effect of the piston at the first cavity is achieved; and meanwhile,