The basement dipping is an important factor controlling the structural deformation of thrust belts. However, rare attentions have been paid on the basement dipping characteristics of the Longmenshan thrust belt. Based on interpretations of seismic profiles, this paper found that the Longmenshan thrust belt in the northern, central and southern segments underwent different basement dipping. The basement dipped 2.6° toward foreland in the northern because of the uplift of thrust sheets. The basement dipped 3. 2° toward hinterland in the central due to several phases of loading. The basement dipped 2.6° toward hinterland in the southern which was the result of earlier rifting and later loading. The numerical experiment shows that the basement dipping toward hinterland or horizontal subsiding will suppress the forward propagation of thrusting deformation, and superimpose the thrusting sheets. While the control effect of the pre- existing basement dip is opposite. When the basement remains horizontal or dip toward the foreland, the thrust sheets in hinterland uplifted stronger than that of the foreland, which will cause the deformation in cover layer toward the foreland as a whole. When the basement dipped backward with syn- sedimentation will result in the back- thrusting in slope zone. Numerical simulation proved the basement evolution in southern segment of the Longmenshan thrust belt. Before the Late Cretaceous, it was in an extensional regime with thick strata in the west and thin strata in the east, which resulting its basement dipping to the west. During the Late Cretaceous- Eocene, a foreland basin developed, and the basement dipped toward hinterland because of the loading. During the Oligocene- Miocene, the thrusting deformation strongly propagated into the basin, and the basement almost had no dipping. Since the Pliocene, the basement in hinterland has been uplifted because of the Qinghai- Tibet Plateau, which resulted in the sharp topography.