There are several reasons for bleeding gums when brushing teeth: 1, gums have damage, due to biting hard objects or eating too hot food will damage the mucosa of the gums, before the mucosa is not restored, there will be bleeding when brushing teeth.2, improper brushing methods, toothbrush bristles are too hard, brushing with greater force and so on, can lead to bleeding when brushing teeth.3, oral diseases, suffering from periodontal disease, due to the oral cavity not clean clean, there is too much calculus accumulation on the teeth, long-term not cleaned up will have bacterial invasion caused by inflammation, bleeding when brushing teeth. 4, endocrine abnormalities, in the sex hormone increase, progesterone hormone increase, teeth stimulation will appear non-specific inflammation, brushing teeth will appear in this case. 5, systemic diseases, there are diabetes, blood sugar is too high, or blood disease, liver disease, the coagulation Function will be abnormal, patients can also appear bleeding when brushing teeth.