Abstract: Bistatic Synthetic Aperture Radar （SAR） has separate transmitting and receiving antennas， which endows the system with flexible structure and strong function expansion. Frequency modulated continuous wave （FMCW）SAR is widely used in air/ground SAR platform because of its low cost. Combining bistatic configuration with FMCW system， spaceborne bistatic FMCW-SAR is applied to satellite platform， which has both the advantages above and is an optional implementation method for future small satellite SAR constellation. At present， the research on bistatic FMCW-SAR high-resolution imaging mostly focuses on the air/ground platform， while there is few research on the space-based platform. Therefore， this paper proposes a high-resolution time-domain imaging processing algorithm suitable for spaceborne bistatic FMCW-SAR system， analyzes the correlation between the distance migration curve after dechirping and the speed of load movement， and proposes a distance migration curve positioning method suitable for space-based platforms， which achieves higher processing accuracy than the traditional time-domain algorithm. The effectiveness of the proposed method has been verified by computer simulation.