Abstract: GPS-interferometric reflectometry can be used to infer temporal changes in near surface, soil moisture content. To estimate reliable GPS interferogram metrics such as phase and amplitude, an improved estimation method based on the GPS signal-to-noise ratio (SNR) data is presented, and a retrieval model for soil moisture content is constructed. Experiments indicate that the improved method is capable of estimating accurate and reliable GPS interferogram metrics as compared to the common method. The SNR phase shows a nearly linear relationship to the soil moisture content. Furthermore, a linear retrieval model for soil moisture content can be achieved, and the model is sensitive to consecutive precipitation.