Abstract: Studies on selenium distribution-and its transforming regularity in different environmental elements of northeast China show that Se contents in bed roch,soil, plant and animal hairs are 0.12, 0.150-0.540, 0.0096-0.0765 and 0.0405-0.1414μg·g^-1,and those in children hairs in urband and rural regions are respectively 0.460 and 0.182μg·g^-1.Based on Se contents in different components and ecological effects,the region is divided into three first-grade areas, e.g.Se suitable area, Se deficiency area and Se transitional area, and each is classified into higher and lower Se source areas.

Key words: Selenium content, Eec-environment, Ecological effect, evapotranspiration, rain-fed area of the Loess Tableland, soil reservoir, soil desiccation, winter wheat