Black spots inside the glans are considered to be caused by pigmented nevus, hyperpigmentation, circumcision glansitis, mycobacterial infection of the glans and other reasons. 1. Pigmented nevus: when there is a nevus in the local skin of the glans, the symptom of long black spots inside the glans can appear. If it is a normal nevus, generally do not need treatment. However, if the skin pigmented nevus is locally irregular and significantly higher than the surface of the skin, it is recommended to go to the dermatology department for consultation, consultation and examination in order to exclude the possibility of melanoma. 2. Melanosis: after inflammation can lead to localized phenomenon of hyperpigmentation. Thus, there are black spots inside the glans, which are normal phenomenon without itching and pain. 3. circumcision glans: when circumcision glans recurs, bacterial inflammation will constantly stimulate the glans area, promoting the formation of black spots on the glans area. 4. Mycobacterial infection of the glans: when mycobacterial glans infection occurs, in addition to causing the glans skin surface to constantly have localized pigmentation, it can also lead to localized edema, erosion, peeling and other symptoms. When the inside of the glans grows black spots, it is recommended that the inner surface of the glans prepuce and the perineum should be kept clean and dry, and to change underwear diligently. If the symptoms are serious, it is recommended to go to the hospital for examination and targeted treatment under the guidance of the doctor.