Usually, the blackening of the glans after circumcision may be related to capillary rupture, tissue ischemia, too tight bandage and other reasons. 1. Capillary rupture: local capillary rupture is caused during surgery, resulting in local bleeding, bleeding accumulates under the skin or tissue for a long time, and after absorption at a later stage, the glans can be seen to have localized bruising and blackening. 2. Tissue ischemia: in the surgical process need to deal with active bleeding blood vessels, after vascular ligation, can lead to vascular distribution area and tissue ischemia, will also appear glans blackening. 3. Tight bandage: local wound bandage is too tight, there can be wound edema, congestion and other symptoms, which can lead to blood reflux obstruction and so on may lead to glans blackening. It is recommended that patients with blackened glans after circumcision should go to the hospital regularly for review, go to the hospital to clean and change the medicine, drink as little water as possible, and reduce the penile erection caused by holding urine.