In order to accurately evaluate the threat to buildings and people’s lives and properties in the run-out path after slope failure， this paper takes a landslide in Chenzhou as an example， simulates the failure mechanism of large deformation under natural and rainstorm conditions after excavation of this slope based on the material point method， calculates the run-out distance， and compares the results with the finite element method. The results show that： （1） Before excavation， the slope is basically stable under natural condition and unstable under rainstorm condition， while after excavation， the slope is unstable under both conditions； （2） The sliding distance of the landslide increases significantly after excavation， and the sliding distance under natural conditions and rainstorm conditions is 20.11 and 24.12m respectively； （3） By comparing the results of stability and large deformation analysis， it can be seen that excavation and rainfall are the two main factors causing slope instability. Calculating the sliding distance after slope instability can provide theoretical reference for evaluating the threat to buildings on the sliding path， and is of great significance for improving slope safety protection.