In view of the shortcomings of the existing light plane calibration, a method of calibrating line-structured light is improved. Firstly, this method uses the improved Steger algorithm to extract the subpixel center of 2 or more laser stripes projected at different heights or angles of the checkerboard calibration board. Secondly, using the constraint of the checkerboard grid world coordinates =0 in Zhang Zhengyou′s camera calibration method, the camera coordinates of the center points of the laser stripes are calculated, and then the ordinary least squares is used to calculate the light plane. A different method from the traditional direct-beam trigonometric method is used to find the height of the object and a new evaluation method is proposed because of no clear standard for the accuracy of the light plane calibration. Experimental results show that the accuracy and robustness of the algorithm are good. For the three blocks with different heights, the maximum of root mean square error is 0.063 mm and the minimum is 0.023 mm.