The invention discloses a closed reciprocating rotary power machine. The closed reciprocating rotary power machine comprises a lead-out shaft, a shaft end clamping device, a protective cover, an elastic body, a flange end clamping device, a transfer flange, a sealing ring, a prime mover, a cover shell, an inner cable, an air plug and an outer cable. The prime mover is a motor or a combination body of the motor and a speed reducer. The closed reciprocating rotary power machine is characterized in that the lead-out shaft, the elastic body, the transfer flange, the sealing ring, the cover shell and the air plug form a sealed cavity; and the prime mover and the inner cable are both positioned in the sealed cavity. When the lead-out shaft rotates, one end of the elastic body is fixed along with the transfer flange, and the other end rotates along with the lead-out shaft, that is, the movement form of the elastic body is winding rotation; and the winding rotation enables the lead-out shaft to only perform limited angle reciprocating rotation. The working principle of the closed reciprocating rotary power machine is to use the elasticity and the tightness of the elastic body for converting dynamic sealing to static sealing so as to effectively solve the application boundedness of dynamic sealing under vacuum environment.