Aiming at the problem that infrared images of substation power equipment are generally blurred and low signal-to-noise ratio, and obvious stitching marks or glistening are easy to appear in the stitching process, an infrared image stitching method of substation equipment based on ROI and improved optimal seam-line was proposed. Firstly, the 50% adjacent area of the two images to be stitching was divided as the ROI to improve the accuracy and efficiency of feature point extraction and matching. Then, the energy difference function of the best suture line was improved by introducing the mean-cosine similarity, so that the best seam-line could accurately traverse the position with the smallest energy difference in the overlapping area. Finally, the experimental verification is carried out to compare the Image stitching effects of three image stitching software Autostitch、ICE and Autopano Giga with the image stitching algorithm based on ROI and improved optimal seam-line in this paper. The results show that the proposed method can effectively improve the efficiency of the overall process of image stitching, effectively reduce stitching traces and glowy phenomena, and achieve high quality infrared image stitching of power equipment.