Abstract: The basic issue of bi-static inverse synthetic aperture radar(ISAR) imaging is studied in this paper using frequency modulated continuous wave(FMCW) radar under the model of bi-static radar systems. Firstly, the echo signal of FMCW radar in bi-static system is analyzed, the coupling terms of range fast time and azimuth slow time which including uniquely in FMCW signal are extracted from the phase of echo signal.Then its forms in range Doppler domain and influences to range profile are analyzed. Simultaneously the corresponding compensation algorithm is applied to compensate the coupling terms. The last simulations show that the proposed compensation algorithm in this paper improves the defocus phenomenon which caused by using FMJCW signal and can achieve good imaging of targets.