Menstrual bleeding is functional uterine bleeding, referred to as meritorious bleeding, is a common gynecological disease, belongs to the category of abnormal uterine bleeding, abnormal uterine bleeding caused by malfunction of the neuroendocrine mechanism that regulates the reproductive system. Functional uterine bleeding is generally considered to be caused by the following factors: first, systemic factors, including adverse mental trauma, malnutrition during menstruation, endocrine and metabolic disorders, iron-deficiency anemia, aplastic anemia, hematological and hemorrhagic disorders, diabetes mellitus, and thyroid and adrenal gland diseases. The second, dysfunction of the hypothalamic-pituitary-ovarian (HPO) axis, includes disorders of reproductive hormone-releasing function, feedback dysfunction, ovulation and luteal dysfunction. The third, uterine and endometrial factors, including structural and functional abnormalities of small spiral arteries, microcirculatory vascular beds, endometrial steroid receptor and lysosomal dysfunction, abnormalities of local coagulation mechanisms and dysregulation of secretion of prostaglandins TXA2 and PGI2. The fourth, medical factors, including steroidal contraceptives, intrauterine devices interfere with the normal HPOU axis function, as well as certain systemic diseases of drugs, such as psychiatric, neurological drugs, can affect the normal menstrual function through the neuroendocrine mechanism, which leads to functional uterine bleeding.