In this paper imaging processing method for Bistatic Synthetic Aperture Radar (BiSAR) utilizing navigation satellite is investigated. Considering the special problems of using Global Navigation Satellite System (GNSS) signal to form SAR image, direct signal is used to estimate range migration parameters and range migration is corrected in azimuth time domain. Doppler sensitivity of phase-coded signal was solved by Doppler compensation. Through fitting the Doppler phase history with high-order polynomial, Doppler phase history is accurately approximated and azimuth compression is implemented by de-chirp processing. Through simulation and experimental data processing, the proposed method is verified.