Hypothalamic amenorrhea (HA), the most common type of secondary amenorrhea, is caused by inadequate pulsatile secretion of gonadotrophin releasing hormone (GnRH) from hypothalamic neuroendocrine cells due to a variety of pathologies in the central nervous system and hypothalamus above the pituitary level. This includes functional hypothalamic amenorrhea, organic hypothalamic disorders, and certain drugs that interfere with the hypothalamus-pituitary-ovarian axis (H-P-O axis). What we usually call hypothalamic amenorrhea refers mainly to functional hypothalamic amenorrhea. This is a reversible amenorrhea that is mainly characterized by a decrease in the function of GnRH secretion from the hypothalamus (including the frequency and amplitude of pulsatile secretion), but without organic lesions of the central or endocrine glands. Hypothalamic amenorrhea is a diagnosis of exclusion, requiring exclusion of other possible causes of central amenorrhea or organic disorders. The hypothalamus is an important reproductive organ. The hypothalamus regulates the function of the pituitary gland through nerve conduction and the pituitary-portal system, causing the pituitary gland to secrete the appropriate hormones, which act on the ovaries to produce steroid hormones and ensure the normal maintenance of reproductive function. The hypothalamus receives stimulation from the central nerve cells to regulate the secretion of pituitary hormones on the one hand, and is regulated by the negative feedback of the hormones secreted by the pituitary gland on the other. Neuroendocrine cells in the arcuate nucleus of the central hypothalamus function by releasing GnRH in a pulsatile manner. There are many causes of hypothalamic dysfunction, such as mental stimulation, sadness and worry, fear and anxiety, stress and exertion, as well as environmental changes, cold stimulation, and strenuous exercise. All of these can cause abnormal GnRH secretion, resulting in non-ovulation and amenorrhea. In the treatment of hypothalamic amenorrhea, the main thing is to find stress factors and remove them, regulate mental tension, especially in adolescent girls who are in the stressful revision phase of high school exams; eat a balanced diet, reduce strenuous exercise, and regain weight. After adjusting the lifestyle, about 80% of patients can resume normal menstruation. The next step is to give hormone replacement therapy, such as Clomid, Fentanyl, etc. A variety of drugs are available. In conclusion, amenorrhea in adolescence deserves attention and needs to be treated early. If treatment is delayed, it will affect the development and reproductive function of adolescent girls, and the hypoestrogenemia of amenorrhea will easily cause bone loss in patients and develop into osteoporosis, as well as bring the risk of cardiovascular disease.