The invention provides a high temperature resistant protective film and a preparation method thereof, the protective film includes a high temperature resistant function layer, a substrate layer composited on the high temperature resistant function layer, a high temperature resistant adhesive layer composited on the substrate layer, and a stripping layer composited on the high temperature resistant adhesive layer, wherein the high temperature resistant adhesive layer is an acrylic adhesive layer or a polyurethane adhesive layer; certain high temperature resistant layers are compounded on both sides of a substrate, the difficult problems of warpage, fogging and residual glue, and the like of an ITO process protective film, and the product quality is good. Moreover, the high temperature resistant function layer not only has high temperature resistant function, but also has high hardness, the hardness is 2-3H, and the high temperature resistant function layer has an anti-scratch function, so that the protective film can be repeatedly used, and the utilization rate is improved.