Abstract: The finite element model of Three Gorges area was built based on DEM and the actual GPS stations' coordinates.The crustal vertically deformation of the Three Gorges reservoir area was calculated under the condition of 135 meter,156 meter and 175 meter water level impoundment by means of the elasticity finite element analysis method respectively.Based on the Farrell's globosity deformation theory,the vertically deformation fields of the Three Gorges reservoir area was simulated under the condition of 135 meter water level impoundment.By comparing the two simulated fields,the mechanism of crustal vertically deformation are analyzed.The deformation isoline covered the valley line with the maximum in Xiangxi segment,and the regional sedimentation is synthetically geological function and the water body gravity as the main reason.