Gas mixing device

The utility model relates to a gas mixing device which comprises at least two gas input pipelines, a mixer, a flow meter and a test box, each gas input pipeline is provided with a first valve, and thefirst valves are used for adjusting the opening degree of the gas input pipelines. And each gas input pipeline is communicated with the mixer. A flow meter is arranged on each gas input pipeline andis positioned between the first valve and the mixer. The end, away from the gas input pipeline, of the mixer communicates with the test box and is used for providing mixed gas for the test box. According to the gas mixing device provided by the embodiment, the first valve can be adjusted according to the gas flow displayed by the flow meter, then the opening degree of the gas input pipeline is adjusted, finally the gas flow required by a test is achieved, and the proportion of mixed gas can be accurately controlled. Besides, expensive instruments do not exist in the gas mixing device, so thatthe device is high in pract