In the verification of pressure gauge, the movement is the main object of work, which is the source of the failure and error of pressure gauge. The movement is composed of center gear, sector gear, hairspring, indication adjusting screw and connecting link. The movement can change the linear displacement of the free end of the bourden tube into angular displacement, and enlarge the small displacement of the bourden tube , so that the pointer can obtain a larger angle proportional to the measured pressure, so as to ensure that the pressure gauge has sufficient reading accuracy and obtain the final indication value.  Only by understanding its working principle can the faults occur smoothly.