The invention provides a dry granulating blast furnace slag waste heat recovery device and a blast furnace slag waste heat recovery method, belonging to the technical field of metallurgy waste residue heat recovery. The device is arranged between a blast furnace and a blast stove, and consists of a granulating kiln for blast furnace molten slag dry granulating, an affiliated pipeline device thereof and a mated deduster thereof. The granulating kiln and the affiliated pipeline device thereof comprise a blower, a molten slag guide groove, an upper sealing valve, a slag storage tank, a sliding nozzle, a lower sealing valve, a relief valve, a balance valve, a granulating kiln gas conveying pipeline, a low temperature particle slag discharging pipeline, a granulating kiln cool air pipeline, a molten slag sprayer pipeline and a granulator. A granulating region and a heat exchanger region are arranged in the body of the granulating kiln. By using the device, solidification latent heat and high temperature particle slag sensible heat of molten slag can be fully recovered, in addition, hot air generated by recovering waste heat is directly supplied to the blast furnace and the blast stove, and the device has the advantages of short material conveying distance, less heat loss in a process, high heat recovery rate, basically no need of second power consumption and small extra investment.