The paper simulates and predicts the conditions after the uranium entered into the groundwater in a disposal site of pre-selected high level radioactive waste in China by using hydrologic modeling software PHREEQC-Ⅱ.The paper also analyzes the different roles of the various influential factors such as pH, dispersity, diffusion coefficient and temperature in the simulation. The results show that the ability of granites in Beishan to adsorb uranium is rather weak and influenced by some influential factors. The results of simulation by software is similar to the experimental results. Therefore, the study will provide an important basis for the safety research on the site.