The invention discloses a method for preparing a graduated color film through a magnetron sputtering machine. The method comprises the following steps that S1, an optical film system is designed; S2,a baffle is designed, and the shape of the baffle is designed according to thickness change of an optical thin film structure simulated by software; S3, vacuum coating is conducted; and S4, color andoptical performance examination is conducted, the color LAB value, visible light reflectivity curve and visible light transmittance curve of a product obtained after vacuum coating are detected, if the test result is qualified, mass production preparation can be made, and if the test result is unqualified, operation returns to the step S1. A transition area of a graduated color film prepared withthe method is natural in gradual color change, the product color is easy to adjust, and graduated color films of different colors and visual effects can be prepared according to user preparations. Compared with electric beam evaporation deposition, a film layer prepared with the magnetron sputtering machine is compact in structure, the refractive index is stable, the film layer is more stable in optical performance, and thus color stability is better.