There are many reasons for the flow of many blood clots during menstruation, mainly for the following reasons: First, it is considered that during the onset of menstruation, the uterus is less able to contract, the endometrium sheds a large amount of menstrual volume, and therefore the symptoms of blood clots will appear, which is a normal physiological situation, but we cannot completely exclude the symptoms caused by diseases, such as submucosal fibroids and other diseases, which can directly affect the appearance of these diseases These diseases can directly affect the contraction of the uterus. Second, endometrial lesions, such as endometrial cancer or atypical endometrial hyperplasia, may lead to increased menstrual flow and clots when menstruation cannot be discharged in time. Thirdly, it may also be caused by functional uterine bleeding or other diseases, which must be treated clinically according to the cause and can have a better treatment effect after active treatment.