Abstract: Sliding spotlight SAR, which is between strip-map SAR and spotlight SAR, is a unique imaging mode. Concerning on the long illuminating time and long accumulating time of high-resolution and wide-coverage-area space-borne sliding spotlight SAR, the precision and the azimuth-time-variant characteristic of the traditional imaging model are analyzed in this paper. Based on the theory of motion compensation for airborne SAR, a method to correct the azimuth-time-variant error, which makes use of range error caused by non-linear movement of space-borne SAR relative to the virtual rotating point, is presented. In addition, a method to compensate the remnant cubic error of the imaging model in Doppler domain is also given here. Finally, a new DCS algorithm with imaging model error mending is introduced, whose validity is verified with computer simulation.