According to the typical moist rainy region subgrade fill, on the basis of the experimental study of the A3 contract section K78+700 (high liquid limit soil) in Ningde Beijing-Taiwan expressway, select typical section by GeoStudio finite element software to carry out numerical simulation research; Consolidation analysis considering the stress and seepage coupling of unsaturated embankment fill to study on the subgrade settlement deformation law in long-term rainfall condition, and then analyze the influence law between long-term rainfall and deformation and compactness, and the relationship between compactness and subgrade settlement. The research shows that the embankment with different moisture content, both in continuous and intermittent construction, the settlement of completion period accounts for the vast majority of the total settlement, the maximum settlement of embankment increases with moisture content increasing in completion period and after settlement stability. When the long-term rainfall occurs, the settlement of embankment and compactness increment are all larger than the no rain period.