The common causes of hard skin on the soles of the feet include callus, metatarsal warts, hereditary palmoplantar keratosis, scaly keratosis pilaris and so on. 1. callus: this disease is mainly caused by long-term mechanical stimulation (such as pressure or friction) caused by excessive proliferation of the stratum corneum. It occurs in the palm and metatarsal pressure and friction parts, appearing yellow or waxy yellow thickened keratinous plate, flat or slightly elevated, the center of the thick edge of the thin, solid texture, the edge of the unclear symptoms. 2. Plantar warts: this disease is caused by human papilloma virus infection. It occurs on the soles of the feet, the initial lesions are small shiny papules, gradually increased to soybean size or larger, due to pressure and the formation of yellowish or tawny callus-like plaques or flat papules, the surface is rough, the border is clear, the texture is hard, and so on. 3. Hereditary palmoplantar keratosis: the etiology of this disease is unknown and may be related to gene mutation. It is characterized by diffuse distribution of hard yellowish keratotic plaques with clear borders and wax-like appearance in the palmoplantar area, often with reddish edges, usually without conscious symptoms. 4. scaly keratinized tinea pedis: this disease is caused by fungal infections such as red trichophyton, trichophyton tinea pedis, gypsum-like microsporidium and flocculent epidermal tinea pedis, etc. It is transmitted through contact, and scratching the tinea pedis area or sharing shoes and socks with the patient is the main way of spreading the disease. Scaly keratinized tinea pedis manifests itself as diffuse skin crusting, thickening and drying of the palmoplantar and heel areas. It is recommended that patients go to the dermatology department of regular hospitals, follow the doctor’s instructions to clarify the diagnosis and treatment.