Previous studies on the sea ice detection based on microwave scatterometers mainly focused on distinguishing sea ice from water, and in turn, exploring the coverage of sea ice. The scatterometer onboard the China-France Oceanography Satellite (CFOSAT), namely CSCAT, uses rotating fan beams to observe Earth surface, such that its multi-incidence and multi-azimuth observation geometry provides new opportunities for sea ice monitoring. In this study, the CSCAT backscatter data are firstly collocated with the sea ice concentration data from the European Organization for Meteorological Satellites (EUMETSAT), and then the seasonal variations of CSCAT backscatter coefficients under different sea ice concentrations are analyzed for both poles. Consequently, the spatiotemporal characteristics of CSCAT backscatter coefficients over the sea ice are derived, and a sea ice geophysical model function (GMF) is developed. The results show that the CSCAT backscatter coefficient increases with sea ice concentration (SIC). Under low SIC conditions, the CSCAT backscatter coefficients show good consistency over south and north Polar Regions, but there is an obvious modulation by wind speed, whose effect decreases as the SIC increases. Overall, the CSCAT backscatter coefficient is closely related to the observation geometry, the sea surface wind speed, the sea ice concentration, and etc. The results provide relevant hints for the SIC retrieval of CSCAT.