Most women of childbearing age have black blood during menstruation, mostly due to poor flow of menstrual blood, which accumulates in the uterine cavity for a long time and then flows out of the vagina with a black appearance. Other patients have black menstrual blood due to inflammatory diseases such as endometritis, adnexitis, pelvic inflammatory disease, and myometritis. This clinical manifestation can also be caused by frequent cold exposure during menstruation and menstrual disorders. Patients are advised to go to a public hospital for internal gynecological examination, pelvic ultrasound, colposcopy and, if necessary, hysteroscopy at the Department of Obstetrics and Gynecology about 3-7 days after menstruation, which can clarify the diagnosis of the disease.