Aiming at the problem of low manual measurement of the size of continuous casting rolls in the sector section in the continuous casting workshop, a continuous casting roll size measurement method based on binocular vision system is proposed. Firstly, the images collected by the binocular camera are preprocessed and the Otsu method was used to segment the background before and after the workpiece; And then, in view of the problem of low edge detection accuracy, the gradient templates of the traditional Canny edge detection algorithm are increased to 8 to extract the workpiece contour, and the sub-pixel level feature points are extracted by combining the polynomial interpolation formula. Then, based on the stereo matching of SAD and Census transformation fusion, the RANSAC algorithm was introduced to eliminate false matching. Finally, the triangulation principle is used to calculate the dimensions of the part. The experimental results show that the average relative error of the system measurement is 0.14%, and the measurement method has high accuracy, and its stability and accuracy meet the task of automatic dimensional detection of continuous casting rolls.