Tea is a kind of functional drink which has important regulating effect on human metabolism. Drinking tea can improve human immunity to diseases and prevent many diseases which are very threatening to human body. Tea contains substances such as theanine，theanine and tea polyphenols，which play an important role in regulating human metabolism. Among the main active components of tea，catechins and their oxides such as theaflavins have significant effects on anticoagulation，promoting fibrinolysis，preventing platelet adhesion and aggregation. Green tea extract，EGCG，etc. can effectively inhibit the absorption of lipolysis products in the digestive tract，and thus play a role in weight loss. In the three stages of tumor development，tea polyphenols can control the mutation of cells from the source of disease through the removal of free radicals，so as to have anticancer effects. Tea polyphenols and oxides have natural non-toxic preservation function；Tea pigment has an obvious effect on reducing fat and oil，and also plays a positive role in weight loss，prevention and treatment of hyperlipidemia and regulation of sugar metabolism.