The invention discloses a pyrolysis device capable of heating denitration urea by introducing high-temperature flue gas. The device comprises a pyrolysis furnace, a boiler, a flue, a flue gas outlet pipe, a dust remover, an air-adjusting channel, a spray gun, an atomization air pipeline and a urea-solution preparation system, wherein the flue gas outlet of the boiler is communicated with the inlet of the flue; the flue gas outlet pipe is communicated with the opening of the side surface of the flue; the outlet of the flue gas outlet pipe is communicated with the flue gas inlet of the dust remover; the flue gas outlet of the dust remover and the outlet of the air-adjusting channel are combined into a pipe via a pipeline and then the pipe is communicated with the flue gas inlet of the top part of the pyrolysis furnace; the interior of the air-adjusting channel is provided with an adjustable baffle; an ammonia-spraying grid is arranged inside the flue; the gas outlet of the pyrolysis furnace is communicated with the ammonia-spraying grid in the flue; the spray head of the spray gun is located in the pyrolysis furnace; and the inlet of the spray gun is communicated with the outlet of the urea-solution preparation system and the outlet of the atomization air pipeline. The pyrolysis device capable of heating denitration urea by introducing the high-temperature flue gas provided by the invention may not rely on an electric heater, and pyrolysis of urea is realized; meanwhile, the cost is low.