Abstract: This paper investigates the contribution of the gravimetry to monitoring deformation in the Three Gorges Reservoir area.Gravity data,especially highly precise gravity data,may remedy the deficiency of GPS and leveling.To describe the 3D image of the crustal movement in this area,these three measurements should be supplementary one another.We can give the deformation characteristics before and after the impoundment by synthesizing these three kinds of data sets.Gravity data not only improves the vertical measurement of GPS but also plays an important role in probing the deformation mechanism and further gives some proofs for monitoring eathquake and landslide.