Based on the RADARSAT-2 full polarization C-band radar data and field survey data,the paper set up the response relationship between backscatter coefficient of different polarization modes and vegetation water content of summer corn, and got the water content of summer corn crop in covered area of Shandong Yucheng. On this basis,it modified the parameters of water-cloud model and obtained the backscatter coefficient of soil components from removing the backward scattering field of the total polarization radar vegetation influence so as to get surface soil water content by radar data of multipolarization. The results show that the correlation between vegetation water content of summer corn and VH, VV scattering coefficient reached significant level, correlation coefficient is 0.86 and 0.79 respectively, the value of VH polarization is better than that of VV polarization; Under the four polarization modes of RADARSAT-2 and the water and cloud model of VV polarization, error sum of squares of theory calculation is the least, which is the optimal polarization inversion type of surface soil water content in the study area.