The invention discloses a non-ferrous metal surface treatment agent and a preparation method thereof. The non-ferrous metal surface treatment agent is characterized in that all components of raw materials are composed of, by weight, 15-20 parts of sodium polyacrylate, 18-22 parts of trifluoroethanol, 3-4 parts of nonyl phenol polyoxyethylene ether, 1-2 parts of sodium dodecyl sulfate, 2-4 parts of sodium citrate, 2-4 parts of EDTA tetrasodium salt, 5-7 parts of chitosan, 4-6 parts of a rust remover, 3-5 parts of a corrosion inhibitor, 3-5 parts of an alkaline cleaner and 2-3 parts of silicon dioxide. The non-ferrous metal surface treatment agent is high in detergency power, good in cleaning effect, free of phosphorus and organic solvent and capable of preventing metal from oxidation and corrosion and keeping the surface of the metal bright, residual liquor generated after cleaning is free of pollution to the ecological environment, a layer of compact protective film can be formed on the surface of the metal, the surface tension and the interfacial tension are lowered, metal ions can be fixed, sensitivity to temperature variation is low, and stability is good; the situation that the mechanical performance of the metal is lowered is avoided, and the strength of steel can be maintained; and the influence on the environment is small, and treatment is more convenient.