Abstract: Based on the 400 g·t centrifugal model test system for dam breaching of Nanjing Hydraulic Research Institute, the centrifugal model tests are carried out to study the breach evolution law and breach mechanism of overtopping-induced breaching of landslide dams by using the "time-space amplification" effect of supergravity field generated by high-speed rotation. The effects of dam height, downstream slope ratio and dam material gradation on the overtopping failure process of landslide dams are investigated by the centrifugal model tests for the first time. The test results show that the breach process of a landslide dam can be divided into four stages, which are surface erosion, retrogressive erosion, erosion along the breach channel, and breach stabilization. Moreover, the peak breach flow is most sensitive to the dam height, followed by the mean particle size. The time to the peak is mainly affected by the downstream slope ratio, and the relative residual dam height after breaching is primarily susceptible to the mean particle size.