The present invention provides a blast furnace smelting slag water quenching waste steam waste heat recovery system. The system comprises a blast furnace slag water quenching apparatus, a slag quenching water circulation apparatus and a waste steam waste heat recovery apparatus. The blast furnace slag water quenching apparatus comprises a smelting slag groove, a water quenching apparatus and a slag discharging and conveying belt. The slag quenching water circulation apparatus comprises the water quenching apparatus, a water circulating tank, a water quenching pump and a water supplying pipe. The waste steam waste heat recovery apparatus comprises the water quenching apparatus, a three-phase separator, a fan, a heat exchanger, a hot water pump and a low-temperature user. The method of the present invention is different from the method in the prior art, wherein the recovery of the slag quenching waste water waste heat is adopted to recover the smelting slag waste heat by the method in the prior art, and the waste heat in the waste steam generated from the smelting slag quenching by the recovered water is adopted to recover the smelting slag waste heat by the method of the present invention, the water quality of the waste steam is better than the water quality of the waste water, such that the disadvantages of high hardness of the waste water, equipment scaling, equipment blocking and the like in the prior art are overcome. According to the present invention, the slag quenching waste steam waste heat is effectively recovered; the system has advantages of energy saving and emission reduction, and environmental protection; the collected waste heat can be used to meet the requirements of the low-temperature user.