The invention discloses a mixed gas charging device for high-voltage electrical equipment. The mixed gas charging device comprises at least two gas charging branches with gas inlet ends and gas outlet ends, wherein each gas charging branch is sequentially provided with a pressure regulating unit and a gas charging unit from the inlet end to the outlet end; each gas charging unit comprises a first throttling valve, a gas flowmeter and a gas charging electromagnetic valve which are sequentially arranged in series, wherein the gas charging electromagnetic valve is connected to the gas outlet end of each gas charging branch, and an air cylinder is connected to the gas charging branch located between the first throttling valve and the gas charging electromagnetic valve. The mixed gas charging device for the high-voltage electrical equipment comprises the at least two gas charging branches with the gas inlet ends and the gas outlet ends; a multi-branch parallel gas charging way is adopted so that a great deal of mixed gas can be charged once; the throttling valves, the gas flowmeters, the gas charging electromagnetic valves and the air cylinders are combined to control the gas charging flow, so that the gas charging proportion of various gases can be precisely controlled; and the mixed gas charging device is easy to implement, the labor intensity of workers can be alleviated and the pipeline is simple.