The utility model discloses a boiler slurry waste heat recovery system which comprises a desulfurizing tower (1), a flash evaporator (3) and a heat pump (4). A sprayer (3-1) is arranged in the flash evaporator (3); wherein the desulfurization tower (1) is communicated with evaporation chambers in the sprayer (3-1) and the flash evaporator (3) respectively to form a slurry circulating loop; a steamoutlet of the flash evaporator (3) is communicated with the heat pump (4), and steam flowing out of the steam outlet exchanges heat with a refrigerant in the heat pump (4), so that the steam is condensed to form condensed water. According to the boiler slurry waste heat recovery system provided by the embodiment of the utility model, on one hand, slurry in the desulfurizing tower is flashed, andthe flashed slurry is conveyed back to the desulfurizing tower, so that the waste heat of the slurry can be obtained; and on the other hand, steam obtained through flash evaporation directly recoverssteam waste heat through the heat pump, the slurry waste heat utilization efficiency is improved, and the cost of the heat pump is reduced.