In this paper, a calibration method for line scan cameras with image distortion is proposed to perform high-precision planar measurement. The intrinsic parameter model is presented according to the imaging work principle of the line scan camera. Moreover, an improved camera model is proposed via integrating the perspective transformation with the extrinsic parameter model in the consideration of image distortion resulting from the non-parallelism of motion direction and object plane. On this basis, the parameters in above model are calibrated based on nonlinear damping least square method with a planar chessboard pattern. A set of measurement experiments are conducted and the results verify the effectiveness of proposed approaches.