First, before calibrating the pressure gauge, a standard pressure source and calibration tools such as a precision pressure gauge need to be prepared. Then, the pressure gauge to be calibrated is correctly connected to the standard pressure source, ensuring a tight and leak-free connection. Next, the pressure value of the standard pressure source is gradually adjusted according to the specified calibration points, starting from zero, increasing to the upper limit of the range in turn, and then decreasing back to zero. At each calibration point, the indication value of the pressure gauge to be calibrated is read and compared with the accurate reading of the standard pressure gauge, and the deviation value is recorded. Based on these deviation data, the error range of the pressure gauge is calculated. If the error is within the allowable range, the pressure gauge calibration is qualified; if it exceeds the allowable range, the pressure gauge needs to be adjusted or repaired, and then calibrated again until it is qualified.