With the developing of space science and technology, the ability of remote sensing and reconnaissance are improved. So higher resolution capability of image system is needed. The resolution of some image system is high in static condition. But image motion or mechanical vibration limits the resolution. The degradation of image quality as a result of motion in the image plane can be evaluated by optical transfer function of motion. A new method to calculated optical transfer function——statistic moments method is discussed. Analytical and numerical methods to calculate optical transfer function of motion are studied when the image moves in the image plane two dimensionally. This method can be used to calculate the degradation of image quality as a result of any kind of image motion in the image plane, and easily used in the case of one dimensional motion.