Abstract: A novel method to obtain the formulations of the return signals in the two dimensional (2D) frequency domain for translational variant Bistatic Synthetic Aperture Radar (BiSAR) is proposed. In this study, the instantaneous Doppler frequency is used and two individual azimuth frequencies are introduced, so that the 2D spectrum can be derived by these two azimuth frequencies. Using the imaging geometry of the general bistatic SAR, the expressions of the two azimuth frequencies can be obtained, as well as the 2D spectrum. Then, the range Doppler algorithm based on the two 2D spectrums is developed to process the spotlight general BiSAR data. Finally, the proposed algorithms are applied to the simulated data and the results confirm not only the accuracy of the derived 2D spectrums for general BiSAR but also the effectiveness of the proposed algorithm.