Based on the analyses of the structure characteristics, running and hydrogological conditions of the uranium mill-tailing site in southern China, the geological and hydrogeological conditions were summarized. Then the one-dimension coupled solute reaction-transport numerical model was employed to simulate the U(VI) migration in shallow groundwater at the site studied here using PHREEQC-II code. The U(VI) concentration distribution as a function of time and distance was calculated and analysed with various diffusing coefficients and dispersion coefficients. The results show that PHREEQC-II code...