In order to solve the problem that the distribution of line structured light is not uniform and it is easy to be affected by the environment, a method for extracting the centerline of line structured light based on quadratic smoothing algorithm is proposed. First, the region of interest of the collected image is cropped to reduce the calculation amount of the laser stripe centerline extracting. Then the gray center of gravity method is used to extract the initial value of the laser stripe centerline, and mean value method is used to smooth the big bulge and burr at the initial position of the laser stripe centerline. Finally, Savitzky-Golay filtering algorithm is used to smooth the small bulge and burr of the laser stripe centerline twice. Experiment results show that, compared with the gray center of gravity method, it is slightly faster than about 0.10 s when using this method to extract the centerline of the laser fringe of the image with a resolution of 1280 pixel×720 pixel, and the accuracy is improved by 19.15% to 44.87%. The impact from the change of light intensity is small. Therefore, the method meets the requirements of good real-time, high precision, and good stability.