Abstract: Grinding concentration is an important factor that can influence particle size characteristics of grinding product. According to the ore property in Shizhuyuan, the particle size characteristics of the first and second grinding products in different grinding concentrations from 60 % to 80 % in laboratory experiments and industrial tests were studied. The results show that the best grinding products with good uniformities, fine dissociation and low useful energy can be obtained at first grinding concentration of 75 % and the second of 65 % in laboratory experiments. In industrial tests, recoveries of eligible products in the first increased 2.23 % and second was 3.96 %, average grading were respectively heightened 1.13 μm and 3.8 μm, reduced degree of over grinding reduced 0.88 % and 1.35 %, grinding technical efficiencies increased 2.79 % and 4.86 %, and incremental use ratios of energy consumption were 4.39 %and 6.12 %. At the same time, the quality of grader overflow products were roundly optimized, eligible fraction increased by 0.72 %, average grading heightened 1.4 μm, and over crushed reduced by 6.76 %. In sum: the steady grinding concentration is necessary for the concentrator.