Abstract: Accuracy analysis is the precondition of a system's production accuracy ensure,through which it is helpful to determine the systemic performance indexs and some technical parameters in order to make the system design easily.In the article,combined with the SAR imaging principles,especially on the basis of presenting the solution of DEM's three dimension coordinates in airborne InSAR system with DGPS/IMU data,deduced the DEM precision influence formulas caused by several errors factors such as base line length,base line inclination,phase difference,distance from the SAR antenna to the ground target points,SAR antenna's position,center Doppler and the plane's velocity,in order to improve the systemic precision then analyzed the main influencing accuracy factors in airborne InSAR system and the systemic realizable performance condition,meanwhile proposed some design suggestions of the airborne InSAR system and made experiments on the real airborne InSAR data.In the article,the results indicated from the methods of accuracy analysis is accordant with the statistical precision using real experimental data,and the conclusions influencing accuracy analysis are correct.