Abstract: A device for opening and closing a cap, includes: a mounting box; a locking pin, rotatably and retractably mounted to the mounting box, and having a locking head for hooking the cap; a guide block, mounted to the mounting box and having a guide groove; a rocker arm, rotatably mounted to the mounting box, and having a first end fitted to the locking pin and a second end fitted with a pin hole; a slidable pin, movably fitted in the pin hole along an axial direction of the pin hole; and an adjusting component, arranged on the second end of the rocker arm and abutting against the slidable pin, and configured to adjust a position of the slidable pin in the pin hole. The slidable pin is coupled with the adjusting component to fit to the guide groove and to slide along the guide groove.