Abstract: A cylinder mechanism includes a cylinder body assembly, a piston assembly, and a grasping assembly. The cylinder body assembly includes a cylinder body. The cylinder body defines a receiving cavity, a first gas hole, and a second gas hole. The first and second gas holes communicate with the receiving cavity. The piston assembly includes a piston movably received in the receiving cavity, a guiding shaft movably received in the receiving cavity, and a limiting member. A first end of the guiding shaft is fixed to the piston, and a second end defines a receiving groove. A pair of guiding hole is defined in the guiding shaft. The grasping assembly includes a pushing member movably received in the guiding shaft, a pin received through the guiding holes, and a latching member movably received in the guiding shaft and capable of protruding outward.