The utility model pertains to the technical field of operation and discloses a blanking device for blast furnace granulated slag which is a technique device for a blast-furnace slag treatment system in iron and steel enterprises. The blanking device consists of a slag ditch; an annular blanking box, the inner circumference surface of which is distributed with water outlets, is arranged at the slag outlet of the slag ditch and connected with a granulated slag device. Slag washing water spraying from the inner circumference of the annular blanking box points to the circle center and the slag and water mixture falls into the granulated slag device. The utilization ratio of the slag washing water is high, slag water rate is low, and the quality of granulated slag is high; therefore, the blanking device can be widely applied in the blast-furnace slag treatment system in the iron and steel enterprises.