Vitamin E is an essential fat-soluble vitamin. It has several basic biological functions such as anti-oxidation, maintaining reproduction, and immune system regulation. The toxicity of over-dose vitamin E mainly manifests in causing negative effects in immunity and the deficiency of other fat-soluble vitamins. This article reviewed biological functions, metabolic characters and safety evaluation of vitamin E to formulate its safety limit dose on animals.［Chinese Journal of Animal Nutrition, 2010，22（4）:817-822］