Tea in China is known as the “national drink”. Tea contains protein, fattiness, vitamins, and polyphenols, caffeine, LPS, saccharine and other components with pharmacological beneficial effects. Green tea is rich in theanine and catechin, it can delay aging and remove free radicals. Polyphenols and their oxidation products in green tea are able to absorb poison of radioactive materials, and thus to help prevent cardiovascular diseases. It can prevent and treat radiation injury. The caffeine in green tea can enhance the excitement process of cerebral cortex and plays a role of refreshing.