Abstract: The deformation monitoring data of the five monitor points in slope engineering is studied thoroughly, especially the influence of startup and reduce convergence time of slope deformation initiated by rainfall, and the deformation law is analyzed. Results show that both of the startup time and the reduce convergence time are obvious hysteresis, which lags the time section of heavy and intensive rainfall about 20 days. Furthermore, rainfall not only triggers the slope displacement's mutation, but also makes its obvious development trend.