As the development of machine vision technology, the color line-scan system is widely applied in the on-line inspection. Due to the non-uniform distribution of optical intensity, the vignetting of optical lens and the different responsivities of charge coupled device (CCD) camera, non-uniform and color distorted image, which induces the problem of image processing and the stability system, could be output from the color line-scan system. A method used in image correction for color line-scan machine vision system is presented. Compared with the polynomial fittings, the mean and variance result of uniform object obtained by this method is better and closer to the real gray of object. The method has been used in the automatic optical inspection of prited circuit board (PCB).