The utility model relates to a waste gas burns burning furnace, especially a waste gas burns burning furnace fuel economizing device. Include and burn burning furnace, burner blower, the diesel oil booster pump, the synthetic tail gas buffer tank, burner blower is through combustion -supporting pipeline and the top intercommunication that burns burning furnace, and the synthetic tail gas buffer tank is through tail gas pipeline and the top intercommunication that burns burning furnace, and cooling blower by freezing pipeline and the lower part intercommunication that burns burning furnace, diesel oil booster pump be through firewood oil pipe way and the top intercommunication that burns burning furnace, tail gas pipeline's entrance point is equipped with the compressed air pipe way that communicates with tail gas pipeline, is equipped with first pipeline between burner blower and the synthetic tail gas buffer tank, the one end and the combustion -supporting pipeline intercommunicationof first pipeline, the other end and the tail gas pipeline intercommunication of first pipeline, be equipped with the second pipeline between burner blower and the cooling blower, the one end and thecombustion -supporting pipeline intercommunication of second pipeline, the other end and the cooling pipeline intercommunication of second pipeline, be equipped with perforated plate structure in thefirewood oil pipe way. Diesel oil consumes, the power consumption, cost is reduced.