Tungsten electrochromic film and preparation method thereof

The invention relates to a preparation method of a tungsten electrochromic film, which comprises the steps of selecting a substrate, preparing a tungsten oxide film and preparing a lithium tantalate film, and is characterized in that a low-hardness C film and a high-hardness C film are sequentially prepared on the lithium tantalate film by adopting a magnetron sputtering method; the preparation parameters of the low-hardness C film are as follows: the power is 500-600W, the Ar is 60sccm, the air pressure is 1.0 Pa, and the time is 10min; the preparation parameters of the high-hardness C film are as follows: the power is 800 to 1000W, the Ar is 80 to 100sccm, the air pressure is 1.5 to 2.0 Pa, and the time is 10min. The preparation method has the advantages that a tungsten oxide film is still used as a main core film layer, a C film is used for replacing a nickel oxide film layer and a silicon dioxide film layer for the first time, and a tungsten film layer capable of meeting all performance requirements in a