The invention discloses a system and method for high-temperature biomass gas cooling and waste heat utilization. A main flue formed by a coal-fired boiler, an air preheater, a dust collector, an induced draft fan and a desulfurization island which are connected in series is included, and a flue gas recirculation pipe, a heat conducting medium-flue gas heat exchanger, a gas-heat conducting medium heat exchanger and a spray drying tower are further included; the spray drying tower is connected to the part, in front of the dust collector, of the main flue, the flue gas recirculation pipe is connected to the part, behind the dust collector, of the main flue, and the main flue communicates with the heat conducting medium-flue gas heat exchanger through the flue gas recirculation pipe; and fluegas of the heat conducting medium-flue gas heat exchanger communicates with the spray drying tower, a heat conducting medium of the heat conducting medium-flue gas heat exchanger is in communication with the gas-heat conducting medium heat exchanger, and gas of the gas-heat conducting medium heat exchanger communicates with the coal-fired boiler. By means of the system and method, sensible heat ofwaste biomass gas is utilized to remove harmful substances in desulfurization waste water, energy saving and environment protection can be achieved, and by-product salt crystals are high in purity and high in added value.