Abstract: The leather solid waste is crushed, solidified and ground into ultra-fine skin powder, and mixed with wood powder and light calcium carbonate as a filler to be added into the polyurethane. The wet leather method is used to prepare the synthetic leather wet base, and the application experiment results show that the ultra-fine skin powder can partially replace the wood powder as a synthetic leather filler, and the addition ratio of the skin powder is discussed. The experimental results show that the suitable application conditions of skin powder are: w (skin powder) ∶ w(wood powder)∶ w (light calcium carbonate) = 15∶5∶25, at this time, the slurry viscosity is 10300 cps, myogenicity is 46.3%, tensile strength is 15.7 MPa, tear strength is 126.6 N/mm, peel strength is 113.4 N/3 cm, hydrolysis resistance is 18 h, water vapor permeability is 2152 mg/10 cm2·24 h, gas permeability is 376 mL/cm2·h. Ultrafine skin powder is used as a synthetic leather wet base filler to reduce cost, improve leveling and feel, and improve skin comfort.