Abstract: Owing to its fixed revisit period, space-borne SAR is suitable for dynamic monitoring the ground information, and change detection is the key processing technology. In this paper Edgeworth approach is used to fit the statistical distribution model of SAR image in different kind of scenes and the Kullback-Leibler divergence is proposed as a measurement of the difference between two SAR images. The idea of integral image is used to improve the calculation efficiency. The difference image is segmented to extract the changed regions, this approach is demonstrated feasible according to the processing test using real satellite SAR image.