The yellowing and hardening of the skin on the palms of the feet is mainly seen in callus, which may also be related to plantar warts and diseases such as tinea pedis. 1. callus, commonly known as callus, is due to the local skin because of prolonged friction and extrusion and the formation of a kind of keratin abnormal hyperplasia, due to its internal blood vessels and nerve passage, so the local can be manifested as yellowing. 2. metatarsal warts, is due to the infection of human papilloma virus and lead to a disease, can be through their own small trauma to spread, the onset of the site of the skin can be manifested in yellowish plaques, and even a slight pressure pain. 3. Tinea pedis, commonly known as foot fungus, is due to infection with fungi, in which keratinized tinea pedis will be manifested as thickening of the skin on the soles of the feet, and the thickened parts of the skin will also show yellowing and hardening phenomenon. As many factors may cause skin changes, the specific situation requires a doctor’s consultation.