Abstract: The objective of this study was to investigate the interaction between microwave backscatter signatures and rice biomass. Our unique data consisted of Radarsat-2 microwave backscattering coefficients at all polarizations (HH, VV, CROSS and HH/VV Polarization) for two rice crop stages. Fresh biomass of the whole plant was measured at the same time in Dongqiao of Suzhou. The study analyzed microwave backscatter signatures in time domain, then built a simple backscatter process model(the water cloud model) and regression models. Analyses based on the water cloud model showed that fresh biomass was better correlated with HH and cross- polarization, correlation coefficient was 0.910, 0.902 respectively, while fresh biomass was best correlated with HH, RMSE was 0.190. The exponent models were better than polynomial models, while fresh biomass was best correlated with HH/VV using exponent model. In a word, HH water cloud model and HH/VV exponent model were optimal to simulate rice fresh biomass