The invention provides a large-diameter slurry shield high-pressure flushing device. The large-diameter slurry shield high-pressure flushing device comprises a water storage tank and a first booster pump set; the first booster pump set is composed of a plurality of first booster pumps connected in series; the inlet of the first booster pump set is connected with a water pump, and a high-pressure pipeline is mounted at the outlet of the first booster pump set; the high-pressure pipeline is provided with two outlets; the two outlets of the high-pressure pipelines both are communicated with the water storage tank; the water storage tank is provided with four outlets, and a branch pipe is mounted at each outlet and communicated with the bubble chamber of a shield machine. The large-diameter slurry shield high-pressure flushing device has the advantages that the high-pressure pipeline, the water storage tank and the plurality of booster pumps are arranged to enable water flow to flush soil around the front gate of an excavation chamber under high pressure, and therefore, the number and the size of soil blocks are greatly reduced and the slurry can be output smoothly, and consequently, the defects of ballasted soil accumulation, easy sticking of clary, easy pipe blockage, unsmooth slurry discharge and the like of the excavation chamber are solved and effective slurry discharge of a shield circulation system and smooth tunneling of the shield machine are guaranteed.