L-glutamine is an important amino acid to compose protein for human body. It has important function on body's activity. It is used as an important biochemical reagent, also used as a promising medicine. It can make mucous membrane of digestive organ regenerate and recover, thus using as effective medicine to cure gastric ulcer and chronic gastritis. Moreover, it can promote the activity of brain nerve to cure neurasthenia and improve the dysmnesia caused by cerebral hemorrhage, prevent from the cancer pain, sustain kidney, pancreas, gall bladder and liver normal function.