Aiming at airborne three-channel SAR-GMTI system and its real data, a novel channel equalization method is presented, furthermore, in virtue of the method's good performance on compensating the clutter differences between different channels, a technique for moving target detection (MTD) and location is further proposed. This method first realizes signal equalization between inner channels utilizing the leaking signals, then implements range and azimuth time calibration and compensates the channel differences via iteration after range compression, after that, it realizes MTD by clutter cancellation and imaging, finally obtains target parameters by estimating moving target doppler shift. The technique proved its good performance in real data processing with the advantages of high channel equalization precision, little computations, good clutter cancellation and MTD performances and easiness to implement.