Take the example of deformation and failure of landslide in Huanglianshu of Three Gauge and according to the monitoring on ground displacement, rainfall, underground water and the reservoir water level, the effects by the interactions between the changes of monitoring parameters and of hazard factors are analyzed and the deformation and failure mechanism are studied. The paper summed up the preliminary study results which not only has important theoretical significance for monitoring and early warning for landslide, but also has reference value and guiding significance for forecasting just before sliding caused by reservoir water level and rainfall.