The invention relates to the technical field of wet bulb temperature measuring devices and provides a high-temperature flue gas wet bulb temperature measuring device. The device is used for measuringa temperature of a wet bulb in a high-temperature flue gas pipeline and comprises a thermometer, a water supply pipeline and at least one water distribution pipeline, wherein the thermometer has a temperature sensing end, and the external surface of the temperature sensing end is wrapped by a water absorption material; a water storage vessel is arranged at one end of the water supply pipeline; theat least one water distribution pipeline communicate with the other end of the water supply pipeline and is used for uniformly distributing water to the temperature sensing end so as to enable the water absorption material to be in a wetting state; the water distribution pipeline is of an annular pipe, of which a plurality of water outlet holes are formed in the pipe wall, and the annular pipe isconnected with the water supply pipeline through a water conveying pipe and sequentially sleeves the external surface of the water absorption material or is located in the water absorption material along the length direction of the thermometer. According to the device, the disadvantage of the existing wet bulb thermometer that moisture in gauze is prone to drying by distillation is overcome, thewater distribution pipe can have sustained water supply, the water absorption material can be in a good wetting state, and the temperature of the wet bulb in the high-temperature flue gas pipeline canbe accurately measured.