Abstract: A compleled method of Calibration of Lens-induced Distortion is discussed,which on a test photographing. It is described as following:take some pictures on a test target; the signs on the pictures are marked and matched by computer automatically; the parameters of lens-induced distortion can be calculated using least square procedure. The algorithm of automatic marking and matching test target is detailed, which contains several approaches:image pre-processing, image binaryzation, image segmentation, sign thinning, line linking, sign recognition, calculating coordinates, grid rebuiding and grid marching. A completed system is implemented based on this algorithm and shows its feasibility and validity in actUal usage.