It is beneficial to extract the parameters of the objects by rich information of PolSAR (Polarimetric Synthetic Aperture Radar) data. With polSAR data of Radarsat-2, the polarimetric character of winter wheat in booting and milk stage is studied based on polarization theory. The results show that: there is a great difference between the polarimetric characters of two stages due to the change of wheat structure. Winter wheat growth can be retrieved by entropy, which changes in different way in the two stages. In booting stage, with LAI increasing, the scattering mechanism tends to be more complex. While in milk stage, with plant density increasing, the scattering mechanism tends to be simpler. The eigenvalue of λ2 is a valuable parameter to retrieve soil moisture with crop cover. Results show the potential advantage of polarimetric radar.