Aiming at the problems of long time consuming and high error rate of large multi-repeating unit PCB image stitching, A fast robust image stitching method was proposed. The collected high-resolution PCB images were sampled down, and image units containing overlapping areas were accurately obtained based on manual points as registration areas; The Shi-Tomasi corner detection algorithm was improved by introducing the suppression radius method to make the extracted regional feature points more evenly distributed; The violence matching method was used to carry out the rough matching of the regional feature points respectively and the registration coefficient matrix was obtained after removing the mismatched point pairs by RANSAC algorithm. Combined with affine transformation formula, the registration coefficient matrix of the original image was deduced and calculated. According to the registration coefficient matrix, the stitched images were fused to obtain a complete PCB stitched image. Experimental verification shows: the proposed image matching method accelerates the speed of large PCB image stitching, and also significantly improve image registration precision at the same time, When the image is downsampled 8 times, Compared with the traditional Shi-Tomsi algorithm and Harris algorithm, the improved Shi-Tomasi algorithm improves the matching accuracy by 7.8% and 4.0%, respectively, which proves the feasibility of the proposed method.