The embankment fills are typically of an unsaturated state. Rainfall infiltration results in deformations of unsaturated fills due to wetting, leading to deformations of embankment slope. Geosynthetics have high tensile strength, which can effectively reduce the deformations of embankment and improve the stability. A constitutive model that considers the hydro-mechanical coupled behavior of unsaturated soils was introduced and implemented in the finite difference program FLAC. Triaxial testing data involving loading and wetting paths were used to validate the constitutive model implemented in FLAC. Using the validated constitutive model to simulate the embankment fill, the deformation behavior of unsaturated reinforced embankments subjected to rainfall infiltration was investigated. The influence of geosynthetic reinforcement on the wetting-induced deformations of embankments was investigated. The results show that the reinforcements have negligible impact in the unreinforced zone. However, the reinforcements could effectively reduce the volumetric strains and shear strains of the soil elements in the reinforced zone. The reinforcements have a negligible effect on surface settlement in the unreinforced zone near the centerline of embankment but are effective in reducing surface settlement at the shoulder and lateral displacements of embankment slope under rainfall. The longer reinforcements are more efficient in reducing surface settlements of embankment and lateral displacements of slope and could also increase the distance between the slope surface and the potential failure surface.