Disclosed are a desulfurization slurry foam treatment system and a working method thereof. The system comprises an overflow slurry collecting tank, an overflow slurry conveying device for conveying overflow slurry and foam to the overflow slurry collecting tank, a foam generation acceleration device for accelerating the generation and discharge of the foam in the overflow slurry collecting tank, an overflow slurry collecting device for recycling the overflow slurry in the overflow slurry collecting tank and a foam eliminating device for eliminating the foam discharged from the overflow slurrycollecting tank. By means of the desulfurization slurry foam treatment system and the working method thereof, the foam is directly conveyed to a vacuum belt conveyor, oil stains, acid insoluble matterand other various substances causing foaming can make the foam broken through the vacuum suction function of the vacuum belt conveyor and remain on the surface of gypsum after filtering of the gypsum, and the removal purpose is achieved.