Based on the data analysis and test results of Jinjiang Reservoir in Guangdong Province, a two-dimensional (vertical section) numerical simulation model of dam seepage based on the finite element method is established. The typical cross-section flow field and seepage parameters of the reservoir are obtained and scientific repair measures are proposed for seepage parts according to the water level and other geological detection parameters of the reservoir for long series. The conclusion shows that compared with historical observation data, the finite element method can simulate the seepage of the reservoir more accurately, and has strong applicability.