Melatonin is a hormone secreted by the pineal gland, and its chemical structure was 5-methoxy-N-acetyl tryptamine, the physiological function of inhibiting gonad, thyroid, adrenal gland, parathyroid gland and pituitary function, inhibit precocious puberty, reduce pituitary Melanotropin secretion; and has a central nervous system function, can improve the convulsion the threshold, cause drowsiness. When pinealectomy after the animal experiment showed hyperplasia of the glands, weight increase, especially sex and sexual organs of immature rats early, pituitary secretion of LH and FSH increased, increasing secretion of thyroid and adrenal cortex hormone melatonin.