Abstract: By analyzing the relation of forward velocity variation and target echoes phase, as well as various kind compensation methods of forward velocity variation for airborne SAR, this paper proposes a new algorithm for forward velocity variation compensation based on data interpolation. This algorithm is to estimate all necessary Doppler chirp rate for the received data using sub - aperture technique, and to extract the aircraft forward velocity by low pass filter , then to compensate forward velocity variation by data interpolation in azimuth direction, hence effectively remove the effect of forward velocity variation for the SAR imaging so as to obtain well image quality. By motion compensation for forward velocity variation and displacement in line of sight, this paper also proposes the airborne SAR imaging algorithm , the imaging results of raw data validate this method robust.