According to the deficiency of the traditional change detection methods used to SAR images

which can not decrease the false alarm caused by the background changes efficiently

a cluster-based approach for detecting changes in SAR images is proposed.This method detects the changes in SAR images by introducing Mahalanobis distance（M-distance）to the different clustered images class

and analyzing the changes of M-distance of the pixels by combining the selection of the change threshold value.The simulation results show this method not only can overcome the negative affects caused by changes of natural environment and background

but also is not influenced by the position of the sensors

and can detect the changes in SAR images at different times efficiently.