A contour-based automatic perspective correction algorithm for circular meters is proposed for the problem of geometric distortion of the collected images in the process of using machine vision to recognize the readings of circular meters. The algorithm is divided into two parts: correction matrix estimation and image correction. First, the correction matrix is calculated by the outline of the circular meter, and then the distorted image is corrected by bilinear interpolation, the algorithm only needs to obtain the coordinate set of the outline of the circular meter to correct the distorted image. The simulation experiment results show that the correction algorithm based on contour can improve the correction accuracy by 2% ~ 6% compared with the traditional four-point projection transformation algorithm, and the actual instrument calibration experiment also shows that the contour calibration algorithm has higher accuracy and stability. It has practical application value for automatic reading of circular meters.