Nutrition and immunity are the hot topics in animal’s production, and the effects of methionine on the immunity are already confirmed as the deep research on the nutrition of amino acid and immune function. However, the relationship of the methionine and immunity has not been elucidated clearly, this review aims to clarify the effects of methionine on immune function in the aspects of growth and development immune organs, the histological structure of the immune organs, non-specific immunity, humoral immunity, cellular immunity and cytokines, and to provide foundations for further studies on the relationship between methionine and immune function.