The male crown refers to the glans and the coronal groove, the phenomenon of blue and purple, mainly considered with the external injury, long foreskin or prepuce and inflammatory stimulation and so on. 1. external injury: the affected area has been hit by external force, resulting in local soft tissue damage, may appear blue and purple phenomenon. 2. The foreskin is too long or circumcised: when the foreskin is opened, the foreskin is embedded, affecting the blood circulation, and the glans and the coronal groove will also appear blue and purple phenomenon. 3. Inflammatory stimulation: diseases such as phimosis, stimulated by inflammation, may also lead to patients with this symptom. This symptom may also be related to other factors. It is recommended that the patient consult a doctor in time to confirm the diagnosis, to be targeted treatment.