The invention discloses an afterheat 
recovery system and an afterheat 
recovery method of dry granulating 
liquid slag. The 
system comprises a granulating cabin, a 
moving bed and an afterheat 
recovery system, the inner surface of the granulating cabin is provided with a granulating cabin 
water cooling wall, the center of the top of the granulating cabin is provided with a 
slag pipe, the 
slag pipe extends into the granulating cabin, the lower part of the 
tail end of the 
slag pipe is provided with a centrifugal granulator, the centrifugal granulator is connected with a motor arranged at the lower part of the centrifugal granulator, the lateral side of the centrifugal granulator is provided with an air supply pipeline, an annular air opening is formed between the centrifugal granulator and the air supply pipeline, the lower part of the granulating cabin is provided with the 
moving bed, the inner surface of the 
moving bed is provided with a moving 
bed water cooling wall, the top of the moving 
bed is provided with an air outlet, the bottom of the moving 
bed is provided with a slag 
discharge device, an air inlet device is arranged above the slag 
discharge device, the afterheat recovery system comprises a primary dust remover, an afterheat boiler, a secondary dust remover, an exhaust fan and a 
chimney which are connected in sequence, and the primary dust remover is connected with the air outlet arranged at the top of the moving bed. The system and the method effectively solve the problems of heat recovery and furnace slag 
granulation of equipment such as a 
blast furnace.