The mathematical model of structure light measurement system is established, and the factors influencing the measurement accuracy are analyzed. At the same time, a fast new light strip center edge extraction algorithm is used in the image processing method, which improves the extraction accuracy distinctly. The accuracy testing experiments are designed and analyzed by standard plate. The experimental results show that the measurement accuracy of this method is better than that of 0.2mm and 0.3mm, and reached in the detection depth and width on the regular groove, which can fully meet the requirements of sub-millimeter small deformation detection accuracy. It is an effective detection method.