The paper studied the model relation of soil moisture and spectral index by using the data field measured spectral reflectance and soil moisture, and analyzed the correlation between the soil moisture and spectral index. Furthermore, based on analyzing the data measured, the research selected the sensitive band and built the optimal inversion model. The soil moisture of the studied area (Maoergai area of Minjiang upriver) was inversed, and then the inversed results were analyzed and evaluated. By analyzing the different inversed results accuracy, the research obtained the optimal method of soil moisture inversion for ecological water information index remote sensing quantitative model.