Fastener driving device

The utility model relates to a fastener driving device, in particular to a nail gun which comprises a shell, a motor, a gun nozzle, a stock bin, an anvil, a driving cylinder, a first piston, a compression cylinder, a second piston, a cylinder cover assembly and the like. The cylinder cover assembly comprises a cylinder cover fixedly arranged with the driving cylinder and a valve assembly, and the valve assembly enables the gas channel to be switched between the opening position and the closing position. The compression cylinder is located outside the driving cylinder and is parallel to the driving cylinder, the gas channel comprises a gas inlet channel and a gas exhaust channel, the second piston acts on the valve assembly so that the gas inlet channel can be located at the open position, and the gas inlet channel can be located at the closed position through the biasing element. According to the nail gun, the second piston acts on the valve assembly to open the air inlet channel to achieve nailing, the struc