The glans is purple behind the coronal groove of the glans, then the possible reasons: first, the foreskin is too long or circumcision patients. For a long time the foreskin wrapped this part, or turn over the foreskin can see the surface of the coronal groove slightly purple, this is a normal phenomenon, is not a disease condition. At this time, the patient does not have any secretion, no local pain may be related to long-term package, local chronic hypoxia and other irritation, it is recommended to circumcision surgery treatment, the color of the foreskin can gradually change to a reddish color. Secondly, when suffering from glans phimosis, there may be a purple coronal groove of the foreskin. It may also be accompanied by local secretions or local erythema, red spots, ulceration and other changes accompanied by local itching or pain. Need to carry out local secretion smear examination, clear whether there is infection. Third, if the weather is relatively cold when the external wash can be found in the coronal groove purple, keep the body temperature warm state can appear to gradually turn to the phenomenon of red. This is mostly related to the environmental temperature without any treatment.