Abstract: Based on analyzing the geometric model of SAR deception-jamming, a real-time deception-jamming algorithm for large scene is proposed. For real-time jamming, a large scene is divided into several sub-blocks and modulated separately. An analysis of jamming range is done according to the depth of focus in range and ambiguity of frequency in azimuth, which provides theroy foundation for blocking partition. By real-time adapting the focus-center of each sub-block, a good focusing image is obtained. Simulation results verify the effectiveness of this algorithm.