Gas mixing device and gas water heating device

A gas-mixing device, comprising:

• a shell, wherein the shell is provided with an air channel for conveying air, a fuel gas channel for conveying fuel gas, and a mixing-gas channel communicating with lower reaches of the air channel and the fuel gas channel, wherein the fuel gas channel comprises a first cut-off portion having a changeable flow area and the air channel comprises a second cut-off portion having a changeable flow area;
• a movable mechanism arranged in the shell;
• and
• a flexible separation component which separates the air channel and the fuel gas channel,
• wherein the movable mechanism penetrates through the flexible separation component and enters the air channel and the fuel gas channel and performs a motion to change the flow area of the first cut-off portion and the flow area of the second cut-off portion, and the flexible separation component is able to deform as the movable mechanism performs the motion.