Abstract: To solve the problems of low recognition accuracy and slow reading speed of the algorithm in reading the indicator of pointer instrument, a reading technology of pointer instrument based on Deming regression and region of interest（ROI） thinning was proposed. The algorithm flow of reading the indicator of the instrument was given. ROI was selected, and the image preprocessing was carried out by the color channel-based silhouette method and binary morphology operation. The image frame difference method was used to eliminate pointer jitter, and ROI thinning algorithm was used to refine the pointer of instrument to be identified. Deming regression method was used to fit the equation and slope of the straight line where the pointer of instrument was located. According to the pointer slope, the angle method was used to calculate the real-time reading of the instrument. Through three sets of experiments, the feasibility and anti-jitter ability of the method were tested, and the detection accuracies of the fitting line by Deming regression and the fitting line by Hough line detection were compared. The calculation speeds of the ROI thinning algorithm and the global thinning algorithm were also compared. The results show that the average error of the proposed method is 37.85% less than that of Hough line detection, and the average calculation time of each image is 192.717 s less than that of the global thinning algorithm. At the same time, the proposed method has the ability of anti-jitter.