Abstract: A pilot study was conducted to optimize the ball milling index of primary stage of the iron processing plant in Baixiangshan, Anhui Province, by measuring the mechanical properties of the ore, screening before ball mill feed. The recommended solution was initially determined as m(Φ60) : m(Φ50) : m(Φ40) : m(Φ30)=20 : 30 : 15 : 35 according to the semi-theoretical formula of segmental ball diameter, and set the big and small solutions as a comparison, and through the grinding comparison test, it was found that the yield of +0.15 mm level decreases by 11.24%, the yield of -0.15+0.10 mm and -0.074+0.019 mm level increases by 6.55% and 9.88% respectively, and the technical efficiency of grinding increases by 7.57%. The discrete element simulation results show that the normal collision energy of the recommended solution is only 4.15% lower than that of the field solution. The normal collision energy of the recommended solution is only 4.15% lower than that of the on-site solution, and the tangential collision energy is 69.04% higher than that of the on-site solution. The recommended solution is better than the on-site solution in a comprehensive comparison.