Abstract: The filling method of high face rockfill dam should be divided in stages. The selection of filling height difference will have certain influence on the deformation of the dam body. FLAC3D is used to carry out three-dimensional numerical simulation of Altash face rockfill dam, and the stress deformation of the dam body is analyzed when the height difference between the upstream and downstream fill body is 5, 10, 15, 20, 25 and 30 m under the form of reverse elevation downstream fill. The results show that the greater the height difference is, the greater the stress deformation of the dam body is, and the worse the stress state of the face plate is. When the height difference is 30 m, the maximum vertical settlement of the dam body is 84.8 cm, the horizontal displacement of the downstream side is 12.9 cm, the maximum principal stress is 2.23 MPa, and the deformation inclination of the downstream characteristic point is 1.02%, exceeding the critical deformation inclination, shear failure may occur. Overall consideration, when designing the filling scheme of high face rockfill dam, great attention should be paid to the selection of the height difference between upstream and downstream filling, and it is recommended that the height difference be less than 30 m.