Abstract: Rainfall is one of the main factors inducing the landslide disasters in ionic rare earth mines. In this paper, with the slope of an ionic rare earth mine in southern Jiangxi as the research object, the changes in pore water pressure of the slope under heavy rainfall were obtained by a numerical simulation method. The influence of rainfall typ, the interval time between rain stops and rainfall intensity on the slope pore water pressure were analyzed respectively, and the coefficient of the slope stability was calculated by applying finite element strength subtraction under the proposed working conditions. The results show that pore water pressures of the slope vary under different rainfall types, and the enhanced rainfall has the greatest influence on the slope stability coefficient. The drop amplitude of the pore water pressure on the slope surface increases with the increase of rain stop interval. When the total rainfall is the same, the shortened rain stop interval is detrimental to slope stability. With the increase of rainfall intensity, the change rate of slope pore water pressure increases, the decline rate of slope stability coefficient increases, and the decline range increases.