At present, the pressure gauge readings are mainly fetched by manual, and there is a reading numerical deviation. The reading accuracy and work efficiency can be improved by using the computer to automatically acquire the pressure gauge readings, so as to realize realtime monitoring. In order to realize accurate and efficient automatic reading of pressure gauge, the computer vision reading based on the Hough transform algorithm was studied and the corresponding program was developed. The number changes of the pressure gauge were collected, and the circular dial was detected by the Hough transformation. The binarization algorithm was used to preprocess the data, and the pointer was refined. The pointer that presents a long triangle was refined into a straight line, and the quadrant position and slope of the refined pointer were determined by detecting the straight line through the Hough transformation. The deflection angle of the pointer was judged according to the slope, and the relation between the pressure value and the deflection angle was fitted by the least square method. Finally, the pressure value of the pointer at arbitrary position was calculated. The results show that the error between the algorithm interpretation value and the actual value of the pressure gauge is between -0.17 MPa and +0.21 MPa, which proves the effectiveness of the algorithm.