A scheme is presented for ground moving target indication with multichannel synthetic aperture radar (SAR). After the effects of different phase centroids are compensated, the images from different channels are used to form an interferogram. Then the probability distribution function of the interferometric phase is estimated as a function of the interferometric magnitude, thus the detection threshold is derived as a function of the interferometric magnitude. Since the detection threshold is magnitude dependent, this scheme has a better performance than the conventional schemes, especially for slow, weak moving targets. The effectiveness of this scheme is verified by both simulated and real SAR data.