Abstract: Edge detection is a basic problem in image processing and computer vision. Its purpose is to identify points with obvious brightness changes in digital images. Laser ranging is an important technical method with the highest accuracy in the field of ranging. Before laser ranging data can be used in scientific research, a series of preprocessing of the original data is required. According to the distribution characteristics of the target signal and noise signal on the image, this paper proposes a method to extract the target signal based on edge detection, which converts the original data into the residual image of distance measurement, and then recognizes the signal position after edge detection. It has been used to process the measured data that the algorithm proposed in this paper has a certain feasibility and versatility.