The image motion of an aerial imaging system was researched and its effects on imaging quality and the resolution of the camera were analyzed. In order to obtain and compensate the image motion of the aerial imaging system, a computation model of image motion based on coordinate trans-formation was proposed. The coordinate transformation model from a ground object to a sensor plane was established by using linear coordinate transformation, and the computation formula of image motion was derived based on the different coordinates of the same ground object during camera exposure. The sources of image shift error of the imaging system were analyzed and the influences of various error factors including the aircraft motion, attitude angle and the camera swing angle on image shift calculation were discussed. Then, the calculation error budget and synthesis with Mont Carlo method was presented. The experimental result shows that the image motion is directly proportional to the velocity of aircraft, and inversely proportional to the distance between aircraft and ground object when the attitude angle and camera swing angle are constant. Furthermore, the calculation error becomes greater with the increase of the parameter disturbance, especially the measuring errors of aircraft motion in longitude and latitude. It concludes that this method is efficient and will be useful to the image motion compensation of aerial imaging systems.