Menstrual black blood clots may be caused by the following reasons: First, the most common and the simplest, clinical women’s qi and blood deficiency, menstruation is mainly composed of blood, when a woman’s qi and blood deficiency menstrual flow will be reduced, the composition of menstrual blood will undergo a certain amount of change, specifically in the color of menstrual blood has become dark, the normal color of menstrual blood is bright red, the color of women’s menstrual blood qi and blood deficiency is dark black, and even black blood clots, the color of menstrual blood. The color of normal menstrual blood is bright red. Secondly, malnutrition can lead to the darkening of menstrual blood or the appearance of black clots, such as women with iron deficiency or lack of vitamin B6, folic acid, etc. can make menstrual blood concentrated, so that the discharge of menstrual blood has black clots, and in severe cases, there is even a temporary cessation of menstruation. Thirdly, women may suffer from gynecological inflammation, such as vaginitis, uterine inflammation, salpingitis, etc., which can cause menstrual blood color to become dark or black clots.