A method to extract a light stripe central line with sub-pixel precision in real time was presented. First, the light stripe was segmented by light stripe contour tracking and the contour polygon representation. Then, based on the counter-clockwise sorting characteristics of contour and the orthogonal relationship between cross section direction and corresponding segmented light stripe direction, the scanning line direction of segmented light stripe was calculated by using a serial representation method. Finally, an adaptive barycenter method that can change adaptively the cross section width was designed on the scanning line to calculate the center sub-pixel coordinates. For the 640 pixel×480 pixel light stripe bitmaps captured by a 3D laser foot scanner with 6 CCDs at typical positions, the extraction time for central line is less than 3.1 ms in sub-pixel precision. The algorithm proposed here can satisfy the requirements of multi-sensor line laser scanning vision measurement system for real time, high precision as well as high speeds.