Abstract: The granule morphology and particle size distribution of milled iron tailings from Qidashan Iron Mine of China were investigated by scanning electron microscopy (SEM), field emission scanning electron microscope (FE-SEM) and laser particle sizer (LPS). The grindabilities of iron railings and blast furnace slag were compared by taking specific surface area as an evaluating index of milling. The results show that the iron ore railings have a much better grindability than blast furnace slag. The milled tailing product obtained by milling for 140 min contains 62.60% grain particles smaller than 5 μm which can fill spaces between cement particles; among them, much smaller particles with submicron or nanometer size were also observed.