Abstract: In order to study the stability of artificial dam body in coal mine groundwater reservoir, the stress environment of artificial dam body construction is analyzed. It is believed that the coal mine groundwater reservoir will form a confining pressure environment around the dam body after water storage. The artificial dam model is established by using FLAC 3D numerical simulation software. The gradient water pressure is applied to the front of the model to simulate the water pressure environment of the reservoir. The simulation results show that: After different confining pressure conditions are applied to the dam body, the difference between the artificial dam body stability and the non-confining pressure condition is obvious. The application of lower strength uniform confining pressure and non-uniform confining pressure will improve the stability of the artificial dam body. Horizontal uniform confining pressure or obvious uneven confining pressure will promote the destruction of the artificial dam. Using the theoretical formula and numerical simulation to analyze the maximum displacement of the artificial dam surface, it is found that the maximum displacement of the dam surface and the reservoir storage height show a good linear relationship. When the confining pressure is low, the dam surface changes. The trend is very small, but the stability of the dam is quite different, which indicates that the stability of the dam can not be accurately reversed by the surface displacement characteristics of the dam.