The invention relates to a finish for a building curtain wall aluminum veneer, and a preparation method thereof. The finish comprises 60 to 70% of FEVE fluorocarbon resin, 5 to 10% of an organic silicon resin, 0.05 to 0.1% of an acrylic acid levelling agent, 0.1 to 0.3% of an organosilicon levelling agent, 0.3 to 0.8% of benzotriazole ultraviolet absorbent, 0.3 to 0.8% of hindered amine light stabilizer, 0.1 to 0.3% of an organotin catalyst, 10 to 15% of butyl acetate, 10 to 15% of dimethylbenzene and 9 to 13% of an aliphatic isocyanate curing agent, wherein the aliphatic isocyanate curing agent needs to be individually packaged and stored and is added into a formula prior to construction for use. The FEVE fluorocarbon resin and the organic silicon resin are utilized as film-forming substances of the finish and the finish can be cured at normal temperature, and thus energy and labor are saved. Through a fluorine-silicon interpenetrating network structure, film surface tension is reduced and a water contact angle is reduced, and thus film anti-contamination properties are improved greatly. Through introduction of silicon atoms, film toughness is improved, and thus a film surface isnot easy to craze and temperature tolerance and endurance are further improved. In addition, the finish has the advantages of simple preparation method and low cost.