The invention relates to a fixed spray flue gas purifying device, particularly to a device for purifying flue gas generated by a domestic waste combustion furnace, and belongs to the technical field of environmental protection equipment. The fixed spray flue gas purifying device mainly comprises a water tank, a deacidification raw material tank, a semi-dry reaction tower, a fixed spray gun, a first fly ash conveyor, an ash storage bunker, an intermediate flue duct, an active carbon storage bunker, a first conveying blower, a Ca (OH)2 dry powder storage bunker, a second convey blower, a second fly ash conveyor, a bag type dust remover, an induced draft fan, a chimney, a tail end flue duct, a third pipeline, a fourth pipeline and an active carbon measuring and feeding device. The device is simple, compact and reasonable in structure, the size of a spray nozzle of the fix spray gun is small, the mounting and maintenance is convenient, and the cost is lower; the reaction tower not only has high degree of finish but also has higher corrosion resistance and wearing resistance, so that the service life is prolonged; standby deacidification equipment is provided to prevent that emission of acid exceeds the standard; and the adsorption efficiency of Dioxin, heavy metal and other harmful pollutants is improved.