Abstract: This paper introduced a method of optimizing the particle size characteristics of ball mill grinding products in wushan by studying the ore mechanical properties to determine matched ball size and ball ratio. Comparative grinding tests were conducted between recommended scheme ( Φ100:Φ70:Φ50:Φ30=15:25:30:30) and plant scheme (Φ100:Φ80:Φ60:Φ40=30:40:20:10) under the condition that the average of protodayknov coefficient of rock strength is 7.8 and average of passion’s ratio is 0.224. Test results showed that recommended scheme achieved the expected performance on optimizing the grinding particle size characteristics that the yield of coarse size fraction ( 0.20 mm) decreased 5.76 percent points, the grinding fineness (-0.074 mm), the yield of easily selected fraction (0.15～0.019 mm) and selectable fraction (0.20～0.010 mm) increased 11.17 percent points,7.63 percent points and 3.52 percent points respectively.