Abstract: A camera calibration method with co-line points is proposed,in which distortion center is located according to cross ratio invariability,and then distortion coefficients are calculated based on a line's central projection is a line.The emulation indicates that only if some measures are adopted to decrease the projection points' coordinate error,error of the distortion center would be less than 2 pixels and relative error of the distortion coefficients would be no more than 0.1.The experiment shows that these distortion parameters gained with the proposed method are good at a correcting distortion image.Because of its easiness and simplicity,this method can be used in some domains such as photogrammetry,computer vision,etc.