The invention provides a cupping glass and a working method thereof, belonging to the technical field of medical equipment and solving the problem that the existing cupping glass is troublesome to operate. The cupping glass comprises a glass body with an opening lower end, the glass body is in internally sliding connection with a piston, the outer edge of the piston props against the inner wall of the glass body, a guide hole is formed in the central position of the end surface of the glass body, the guide hole is in internally sliding insertion with a pull rod, the inner end of the pull rod is connected with the upper end surface of the piston, a positioning block which can fix the pull rod when the piston is upward moving is arranged on the pull rod, and an adjusting piece which can adjust the interior vacuum degree of the glass body after the pull rod is fixed is further arranged on the pull rod. The cupping glass is convenient to operate, the interior vacuum degree can be adjusted, and the usage is more flexible.