Soil moisture is a key component in the hydrologic cycle and climate system. It is an important input parameter for many hydrologic and meteorological models. Taking the advantage of the multi-incident angles of the ERS Wind Scatterometer(WSC), a new soil moisture retrieving method, that significantly improves the surface backscattering presentation, is proposed in this study based on the Advanced Integral Equation Model (AIEM) and the Water-Cloud model. It utilizes the correlations in each backscattering components (bare soil and vegetation) for the simultaneous measurements of each incident angle pairs to reduce the effect of surface roughness and vegetation scattering on soil moisture estimation. The result is validated by using the ground measurements from the Intensive Observation Period (IOP’98) field campaign in 1998 of GAME/Tibet in the end of this paper, and the time series of the estimated soil moisture shows a consistent trend with those sampled on the ground.