A cylinder mechanism includes a cylinder body, a piston pole slidably installed to the cylinder body, a connecting member mounted to the piston pole away from the cylinder body, and an adjusting apparatus. The cylinder body includes two tabs protruding out from two side surfaces of the cylinder body. Each tab defines a guiding hole extending along a moving direction of the piston pole. The adjusting apparatus includes two screws and two adjusting nuts fitting about the two screws. A first end of each screw is mounted to the connecting member, and a second end of each screw is passed through the corresponding guiding hole. Each adjusting nut is connected to the second end of the corresponding screw, and the adjusting nut is configured to abut against the corresponding tab. The stroke of the piston pole is configured to adjust according as rotating the adjusting nuts.