A new algorithm is presented to indicate ground moving targets in synthetic aperture radar images. Two filters, which differ only in the signs of the phase responses, are used to defocus the complex image respectively. In the two defocused images, each stationary target is blurred to the same extent, but each moving target is blurred to different extents. Therefore, moving targets can be indicated by the patch-by-patch sharpness comparison of the two defocused images. The results of the simulated and real data show that this algorithm is effective and efficient.