In order to improve the accuracy of case three-dimensional measuring system based on structured light, the extraction method of light stripes center based on Hough transform and least square was proposed. Firstly, the target structured light was segmented by the median filter and threshold segmenting method which uses the difference of R, G and B in color model. Secondly, multiple iterative thinning was used to deal with the green light area and red light area respectively to obtain their skeleton. Thirdly, the points were classified according to the lines which are obtained by Hough transform. Finally, least square was used to fit the points sectionalized and obtain the center line. A series of experiments have been performed to test the proposed method. It is proven that the proposed automatic extraction method is effective and advanced.