[en] It is of great importance for soil covering as radon suppression approach in uranium mining and metallurgy site decommission. The results of soil covering test can provide scientific basis for the design and environmental impact assessment of decommissioning work. Two typical uranium mining decommissioning sites, waste rock heap and tailings are studied. According to the soil covering test results, the relationship between radon flux rate, soil thickness and diffusion coefficient of two kinds of sites are discussed, and the corresponding function is established. The results show that the thickness of overlying soil is significantly related to the radon suppression effect of two kinds of covering sites. The research results can be applied to guide the onsite project. (authors)