For space optical remote sensor (SORS) with either film or TDI-CCD imaging, to achieve higher resolution requires more accurate real-time image motion compensation. This primarily depends on real-time computation of the image motion velocity vector (IMVV) and error budget and synthesis on related parameters. An effective modeling scheme is introduced and the derivation of IMVV equation, error budget and synthesis by Monte-Carlo method are presented in detail. This total solution was applied to SORS system field test and has been confirmed to be very accurate based on the resolution, transfer function at Nyquist frequency, signal-to-noise ratio and average gray scale of the captured images.