There are several reasons for women to have black vaginal flow: First, there may be gynecological inflammation, such as common endometritis, pelvic inflammation, vaginitis, tubal inflammation, uterine cavity inflammation, etc. Because most of what causes gynecological inflammation are bacteria, so when women suffer from gynecological inflammation, the secretion substances of bacteria and the destruction of the skin mucosa of the lesion by bacteria, the necrosis and shedding of tissue cells, etc. The abnormal secretion material can be formed, and these secretion material will be black. Secondly, for women above the age of 40, if there is a sudden flow of black things below, we should suspect whether there is a malignant tumor formation, such as common cervical tumor, cervical cancer, endometrioma, uterine plasmacytoma, uterine cavity tumor or vaginal transverse myoma, etc., which can cause necrosis of tissue mucosa and cell shedding, these combined factors can lead to the formation of black things below.