Abstract: A review is presented here of (1) the natural ecological environment of selenium; (2) the content, distribution, form and transformation of selenium in the global soils;(3) the key factors determining selenium content in plant and in food chain;(4) the relationship between selenium absorption and accumulation of plant and its genetic factors;(5) the major forms of selenium existing in plant tissues; (6) the relations between the forms of selenium with its bio availability and bio utilization rate;(7) the methods for regulating selenium level in food chain; and (8) the frontier issues for future research on selenium.