The go-stop mode is not suitable for Frequency Modulated Continuous Wave Circular Synthetic Aperture Radar(FMCW CSAR), the Doppler shifting caused by motion of the carrier aircraft has a great effect on the quality of imaging under large-scale, high-velocity condition.The compensation functions of linear SAR are not applicable due to the continuous change of the velocity direction.To solve the problem, we established an accurate signal receiving model, deduced the Doppler shifting in FMCW CSAR, analyzed the effect of the motion radius and velocity on Doppler shifting, and proposed a new compensation function to revise the Doppler shifting.Simulation results proved that the function can correct the Doppler shifting effectively.