Abstract: Firstly, principles of internal calibration technique are introduced in airborne synthetic aperture radar (SAR), and the real-time transmission signal data of SAR send calibration is analysed. Then, the performance indicators of one dimensional range image are given with and without the systematic errors compensation, meanwhile, a method is proposed using the real-time calibration data as reference functions in SAR image processing. Finally, the successful radar flight test and the high resolution range profiles have proved the feasibility of this method.