Abstract: Based on optimizing the grinding process of oolitic hematite,the effects of sodium hexametaphosphate,sodium tripolyphosphate and Z-164Don the grinding efficiency of oolitic hematite were studied.And the results showed,keeping other grinding parameters as constant and the grinding concentration being 80%,the contents of-0.074mm in the grinding products were increased by 30.25, 29.83and 30.15percentage points respectively under the proper dosages of all three kinds of grinding aids. However,comparing with the optimal grinding conditions without grinding aids,the contents of-0.074 mm in the grinding products were only increased by 0.72,0.30and 0.62percentage points respectively when the grinding concentration was 70%.On the basis of experiments and measurements,the changes of pulp viscosity,the particle morphology and the surface hardness of grinding products were studied and the mechanisms of improving the grinding efficiency of oolitic hematite by grinding aids were revealed.