The black thick menstrual blood flow is caused by a small amount of menstrual blood that stays in the uterine cavity for a long time causing the color to change and mixes with the shed uterine lining before being discharged. A variety of reasons may cause the menstrual blood to be too small and dark in color, such as women who often crave cold food or women who are invaded by cold in the cold winter, living in a cold environment for a long time, often using air conditioning and blowing cold air, etc., all of which may lead to the invasion of cold and invade the uterus and lead to the abnormality of menstrual blood, which will be dark and thick and have a small amount of blood. When this symptom occurs, the patient should promptly go to the Chinese medicine department or gynecology department of public hospitals, the specific medication should follow the doctor’s instructions, usually pay attention to good personal protection, pay attention to the uterus to keep warm, to avoid the stimulation of cold.