Considering the problems that it would induce disasters of the waste dump near a city under heavy rainfall, four kinds of heavy rainfalls were designed. Using modeling function of ANSYS software, a model for the waste dump stability was established. The ABAQUS finite element analysis software was utilized to analyze fluid-solid coupling of unsaturated soils. Four kinds of heavy rainfalls were imposed on the dump. also considering that the permeability coefficient of soil was influenced by soil porosity ratio and moisture content. By monitoring wheather there was an abrupt increase in displacement of characteristic places of finite element and whether plastic deformation area cuts through the dump, whether or not there was a failure of the risk was judged. Besides, whether the finite element numerical calculation was convergence was used to solve the factor of stability. The results showed that, the waste dump might slide in the case of rainfall intensity larger than 30.72 mm/h and its duration longer than 30 minutes, this reminded the relevant departments to prepare for disaster assessment and risk prevention.