The invention discloses a disintegrating slag afterheat utilizing system. The disintegrating slag afterheat utilizing system comprises a disintegrating slag tank, wherein a deslagging port at the bottom of the disintegrating slag tank is communicated with a slag sluice, the disintegrating slag tank is communicated with the top of the slag sluice through a steam discharge pipe, the slag sluice is communicated with a sedimentation tank, an overflow baffle plate is arranged in the sedimentation tank, a hot water supplying and feeding pipe is arranged in the sedimentation tank and is connected with a heating water heat exchange device which is communicated with a cold water pond, a cold water supplying and feeding pipe is arranged in the cold water pond and is connected with the disintegrating slag tank, a spraying branch pipe is arranged on the cold water supplying and feeding pipe and is connected with a spraying pipe in the slag sluice, and the heating water heat exchange device is connected with a heating unit. The disintegrating slag afterheat utilizing system has the advantages of being free of influence of impurities in disintegrating slag water, being capable of recycling heat in disintegrating slag water, being contributed to saving of energy sources, reducing the pollution of iron and steel enterprises to environments, and recycling heat for heating so that the heating expenses of enterprises are saved.