Edge detection technology applies in the electric power industry more widely, But there are still a little problems limiting its practical application in engineering. For complex on-site power equipment image, using the optimal threshold gray segmentation and Canny edge detection technology, put forward detecting the electricity equipment image based on improved Canny operator. First, use the optimal threshold gray segmentation to determine the Canny high threshold Th, which play a decisive role in edge detection; and use the corresponding relation to determine low threshold Tl, which Play a supplemental role in edge detection, thereby can realize that the improved Canny operator adaptively detects the electricity equipment image. The experimental results show that, this method can achieve the desired edge detection, and has a certain practical.