Stepless adjustable type slow ignition device

The utility model relates to a stepless adjustable type slow ignition device, which is an ignition device for gas water heaters. The utility model comprises a water valve subassembly, an air valve subassembly, a gas distributing pipe, a burning device and an ignition subassembly of the burning device, wherein, the water valve subassembly is provided with a unidirectional valve; the gas distributing pipe is arranged on the water valve subassembly and the air valve subassembly, and is communicated with the air valve subassembly; the burning device is communicated with the gas distributing pipe. The utility model is characterized in that the water valve subassembly is provided with a flow adjusting member which comprises quantitative micropores arranged on the valve wall of the unidirectional valve, external threads positioned on the peripheric surface of the unidirectional valve, and internal threads inosculating with the external threads of the unidirectional valve, wherein, the internal threads are arranged at an appropriate position on the water valve subassembly where the unidirectional valve is positioned. Consequently, the uniformity of the slow ignition time of a water heater can be realized.