Abstract: Silty soil has obvious characteristics of unsaturated soil mechanics. The failure of silty slopes induced by change of water level inside and outside them is one of the most common engineering disasters. Two centrifugal model tests associated with the corresponding theoretical analysis and numerical simulation of unsaturated soil mechanics are carried out. The two model tests reveal the deformation, sliding mode and failure mechanism of the silty slopes. The test and numerical results show that if the water level inside the silty slopes is higher than one-third of the slope height, multi-landslide will progressively occur from the toe to the top and from the shallow layer to the deep one. The rise of the outside water level causes obvious collapse deformation inside the slope, and the drawdown of outside water level results in shallow multi-landslide. The failure of the silty slopes is closely related to the behaviors of unsaturated soils. Finally, a series of engineering measures to control the failure of the silty slopes are proposed.