Abstract: InSAR motion compensation is a key step to obtain high-precision product. The effect of MOtion COmpensation (MOCO) errors on the precision of airborne dual-antenna InSAR is analysed. First, the MOCO residual errors are deduced on condition that the referenced DEM (Digital Elevation Model) is accurate or not, respectively. Next, the effects of MOCO errors on the interferometric phase and plane location are analyzed without measurement errors considered. Then the effects resulted from trajectory measurement errors and baseline measurement errors are presented. Finally, the accuracy of the theoretical deduction is verified with simulation and real data. The research provides theoretical bases for the system design and signal processing of airborne dual-antenna InSAR.