A comparison study has been made between the properties of blast-furnace slag powders(BFSP) ground by ball mill(BFSP-B) and vertical mill(BFSP-V), respectively.The Blaine specific surface area of the powders ranges from 458 to 606 m~2/kg.The results indicate that the particle size distribution of BFSP is in accordance with Rosin-Rammler,the particle size distribution of BFSP-B is wider than that of BFSP-V.The general coarse-fine grade of the two kinds of ground slag powder can be accurately characterized with both specific surface area and median diameter(d_(50)).The internal friction angle of BFSP-V is less than that of BFSP-B,so it's fluidity is better.