Abstract: Time and frequency synchronization errors exist in the bistatic SAR based on spaceborne transmitters because the transmitters and receivers are mounted on separated platforms. Time and frequency synchronization error will affect the imaging, even lead to abnormal imaging. Therefore, Time and frequency synchronization is a key problem in this kind of system. Focused on the bistatic fixed-receiver SAR based on spaceborne transmitters, the time and frequency synchronization error model is analyzed firstly, and then, a time and frequency synchronization approach using direct-path echo is presented, in which we obtain the time and frequency error from the peak position and phase of direct-path. Finally, simulations are carried out to prove the validity of the proposed method, and its performance was also examined. Simulation results show that the approach achieves excellent performance, and can be applied effectively in the above-mentioned bistatic SAR systems.