The darkening of the spine may be caused by physiological factors or hidden spina bifida and other factors. 1. Physiological factors: If the backbone is exposed to the sun and wind for a long time, excessive friction may lead to localized pigmentation, resulting in the blackening of the spine. 2. Occult spina bifida: it is a congenital malformation, which is a kind of common occult vertebral canal closure insufficiency in clinic, and can lead to localized skin pigmentation, scoliosis, lumbago and other symptoms of the patient, thus appearing the spine blackened. Normally, attention should be paid to sun protection, wear loose and breathable clothes, if the spine blackened, or accompanied by other uncomfortable symptoms, should be timely consultation, so as not to delay the condition.