Abstract: It is needed for the SAR processor to produce continuous image of the pre-scheduled mapping region in a real-time reconnaissance system, but the discontinuous and seams exist between adjacent image frames of airborne UWB SAR, which comes of data-division processing method and real-time motion compensation, will greatly influence the precision of image frame mosaicing. Based on the discussion of real-time processing structures and motion compensation, a quantitative relationship between the conference track selection and geometric distortion is analyzed, and then a real-time geometric distortion correction procedure is put forward with the analysis and of the correction error. In the end, the simulation result of point targets is used to testify the correctness of the former analysis and correction procedure, and a mosaicing example of two adjacent airborne UWB SAR image frames before and after geometric distortion correction procedure is present in the final.