The invention discloses a high-performance TPU (Thermoplastic Polyurethane) modified thin film and a preparation method thereof and in particular relates to the technical field of preparation of TPU modified plastic. The modified thin film is prepared from the following raw materials in parts by weight: 75 parts of TPU particles, 10 parts of rubber, 2 parts of sodium potassium silicate, 3 parts ofa flame retardant, 6 parts of natural polyphenol, 15 parts of epoxy resin, 12 parts of polyester staple fibers, 6 parts of a flatting agent, 10 parts of a friction-resisting agent, 2 parts of an environment-friendly plasticizer, 7 parts of a light degradation agent and 12 parts of starch. The modified TPU thin film has the advantages of high productivity, high surface glossiness and the like; meanwhile, the modified TPU thin film also has excellent functions of high water resistance, wear resistance, moisture permeability, wind-proof performance, cold-proof performance, antibacterial performance, anti-mildew performance, warm-keeping performance, anti-ultraviolet performance and the like; the natural polyphenol added in a preparation process can be used for effectively enhancing the yellowing resistance of the thin film; a formula contains a starch material, so that the production cost can be reduced, and the degradation time is accelerated; no air pollution is caused in an incineration and combustion process and the modified TPU thin film has a good protection effect on the environment.