SAR radiometric calibration is the premise of object backscatter coefficient inversion using image intensity and the calibration accuracy directly affects the subsequent quantitative remote sensing technology application. Airborne platforms is vulnerable to air turbulence and then its attitude is unstable, resulting in SAR antenna radiation power’s fluctuation in azimuth, thus reduces the radiometric calibration accuracy. The traditional twodimensional space variant radiometric calibration method can compensate this error, while this method is effective only in the integration method. This paper proposes an improved method which not only can get good calibration results with both integral method and peak value method, but also can improve the index of the point target’s impulse response width and peak sidelobe ratio. Simulation and real data processing results show the effectiveness of the improved method.