Abstract: Radar can acquire remote sensing information in all-weather. This is the urgent demand to monitor crop growth in some key phenophase. With polarimetric radar of Radarsat-2 data, the backscattering coefficients of winter wheat in booting and milk stage was studied based on MIMICS model. The purpose is to analysis the backscattering characters of winter wheat in different phenophase and to get the method of parameters inversion. The results showed that there was a great difference between the backscattering of the two stages due to the change of wheat structure. Model can give the reference of growth inversion, and give the theory basis of crop parameters inversion. The ratio of HH/VV can extract growth information in booting stage, while with ratio of VV/VH in milk stage with higher accuracy. Also, the ratio of VV/VH can estimate the yield of winter wheat in milk stage.