Abstract: An error modeling method of synchronous belt motion controller based on the orientation calibration is proposed. The steps are:(1)restoring the homography between the known point coordinates and the image plane coordinates on the different positions of motion axis, then obtaining the interior and exterior orientation elements of the camera; (2)calculating the corresponding positional relationships between different positions by linearly operating the translation vectors in exterior orientation elements; (3)regarding the distance corresponding to pulses that you input as the true value, which can do the differential operator with the positon relationships previously calculated to obtain multiple sets of error data, then establishing the polynomial error model by fitting. Experiments show that the error modeling method needs less equipment and simple operation, and the model precision can reach to sub-millimeter level.