The atmospheric diffusion and concentration distribution of radon (emanation rate is 6.06 Bq/m2s ) emanating from the flat ground uranium tailings impoundment at various heights(0m, 10m, 20m, and 30m) are simulated. The numerical results show that the different height of the tailings impoundment will mainly influence the radon concentration that could change in the range of 16∼250 Bq/m3 at the downwind region of 0-300m. The radon concentration and annual effective doses for public from radon decrease sharply with the increasing distance away from tailings impoundment, are higher than that ...