Abstract: A new method for the motion compensation of the airborne strip-map SAR is presented. The motion parameters are computerized from the estimated Doppler rates which are distributed along the range according to the motion of the phase center. So a spohisticated motion measurement system is unnecessary in certain conditions. Another advantage of this algorithm is that the phase compensation rather than the complex interpolation is involved in the compensation of the variation of the along track veolcity, hence the high computational efficiency and the improved image quality. Theoretical analysis and the real data images show that it is of great value in real-time imaging.