At present, pointer pressure gauges are often calibrated using image method, but there are some problems in the measurement process, such as difficult to segment the pointer of the pressure gauge, difficult to separate the background and low recognition accuracy. In order to solve the above problems, combined with the appearance size of the pressure gauge dial of different specifications, the automatic measurement and calibration system of the pressure gauge is studied. Firstly, the optimal working distance between the camera and the pressure gauge is automatically determined according to the external dimension of the pressure gauge dial within the field of view of the industrial camera. Secondly, the image sharpness is evaluated by the image edge gradient value, and the camera focusing is automatically completed. Finally, the polar coordinate transformation method is used to realize the functions of scale line positioning, pointer extraction, real-time reading and so on. The test results show that the system is suitable for the calibration of pointer pressure gauges with shell diameters of 40, 60, 100, 150, 200 and 250 mm.