Abstract-For multi-channel SAR system, since the minimum antenna area constraint is eliminated, wide swath and high resolution SAR image can be achieved. However, compared to mono-channel SAR system, there exist many deleterious factors in multi-channel SAR system which significantly degrade the quality of SAR image. In this paper, all the deleterious factors in the system are analyzed and classified according to their impact on the SAR imaging processing, in addition an new array error estimation method is presented. The validity of the proposed method is verified by experimental results of measured Tri-channel SAR data.