The skin on the feet is black, if it is a short period of time to form this black, then it may be a local blood circulation obstacle, need to go to the hospital in time, because it may be caused by blood clots. If it is a long time gradually formed the color black, may be a chronic eczema caused by a kind of pigmentation, but also may be the lower limbs of the blood circulation obstacles and the formation of the deposition of ferritin, because the color of ferritin happens to be black-brown, so longer, the formation of the dorsum of the feet of the skin has a black performance. For these several cases of black skin also need to be treated differently.