In order to find out some endemic desease in relation to environmental selenium,the content and the regular distribution of Se in soils of selenium-rich area in Ziyang county have been studied,and the relationship between the soil available Se and soil properties has been discussed.The total Se contents of soils varied with the parent material and sail-farming condition,and the average content of total Se was 0.323 mg/kg,the water-soluble Se content ranged from 0.1% to 0.9%,and the KHzP04-extracted Se from 1.1 % to 3.8%.Selenium-rich rocks and soils were found to be only distributed in the limited areas.According to the geographical distribution of Se in soils of Ziyang county,Four areas could be distinguished follows:1.selenium-toxic area,2.high-selenium area,3.medium-stlenium area,and 4.low-selenaum area.The Se content of topsoil was the highest,and it decreased with the depth progressively in the soil profile.The degrees of seven soil factors affecting the KH₂PO₄-extracted Se:CaCO₃>silt>organic matter>clay>pH>free iron>CEC.The analytical results of the soils and plants have proved that the KH₂PO₄-cxtracted Se could reflect the situations of Se supplied by the soil.