Abstract: For distributed spaceborne single-baseline SAR-GMTI systems, SAR-ATI and SAR-DPCA are the two ordinarily exploited clutter suppression and moving target detection techniques. Based on the signal model and statistical model of the two clutter cancellers, the detection performance of ATI and DPCA are analyzed and compared, with a consideration to the channel amplitude/phase unbalance error, time/frequency synchronization error and the influence of clutter and noise. Simulation experiments demonstrate that DPCA is better than ATI under the homogeneous area assumptions. Channel amplitude/phase unbalance error are important error to performance degradation. After some preprocessing steps, frequency synchronization error are not very serious.