The invention provides cold-resistant, solvent-resistant and yellowing-resistant surface polyurethane resin and a preparation method thereof and relates to the technical field of high polymer materials. The polyurethane resin is prepared from the following raw materials: diisocyanate, a polyol compound, a dihydric alcohol chain extender, a diamine chain extender, a catalyst, an assistant, a solvent and n-butylamine. The surface polyurethane resin is all-polyester polyurethane resin, has good cold resistance, solvent resistance and yellowing resistance, and completely meets the leather forming requirements of shoe leather. The surface polyurethane resin is easy to operate in a leather forming process, and finished leather is excellent in oil resistance and cold resistance.