Abstract: Current experimental research on the breaching of landslide dams primarily focuses on overtopping failure, while there is limited understanding of the characteristics of the piping-induced breaching process. This study conducts large-scale physical model tests to investigate the mechanism of piping-induced breaching in landslide dams. The experimental results indicate that: ① Based on the characteristics of different stages of piping-induced breaching, the process can be divided into three stages: the pipe channel expansion stage, the rapid development stage, and the stable development stage; ② Under the same conditions of dam dimensions, construction materials, and inflow, the mechanisms and processes of piping-induced and overtopping-induced breaching differ. Piping-induced breaching lacks the stage of retrogressive erosion by headcut, as failure initiates at the downstream seepage exit and progresses upstream, ultimately resulting in instantaneous collapse due to weak zones at the dam crest. In contrast, overtopping-induced breaching involves gradual expansion of the breach under the action of water flow (progressive erosion and headcut erosion). During the rapid development stage, both types of breaching involve the widening of the breach due to instability and collapse of the dam slope. However, the incision processes differ: in piping-induced breaching, the bottom elevation is relatively low due to prior development, resulting in a smaller magnitude of incision. Instability and collapse of the sideslopes are triggered by toe scour. In overtopping-induced breaching, the bottom elevation is higher, and rapid incision of the breach is achieved through erosion by high-velocity flow, coupled with large-scale slope instability and collapse; ③ During the rapid growth stage, the peak discharge of piping-induced breaching is greater than that of overtopping-induced breaching.