The properties of copper ores in a copper concentrator in Jiangxi Province have changed greatly since August 2016，which resulting in obvious differences in particle size composition of grinding products，large consumption of grinding media and reduction of copper recovery rate in the flotation process.Starting with the size and proportion of grinding media，through the determination of ore properties， comparative grinding tests and industrial application work，the purpose of improving the quality of grinding products and copper sorting indexes and reducing the steel ball consumption can be achieved. The mechanical properties of 16 ore blocks with specifications greater than 200 mm were determined on a press of model DE50A.According to the measurement of rock mechanical properties，the average values of Pushi hardness coefficient f and Poisson’s ratio of the porphyry copper ore in this concentrator are only 5 and 0.155，respectively，belonging to soft and brittle ores.The comparison test of copper ore grinding in the concentrator was carried out in a 450 mm× 450 mm discontinuous ball mill in the laboratory.According to the mechanical properties of the ore and the grinding conditions in the field， the maximum grinding ball diameter was calculated to be 70 mm， and four groups of grinding test schemes were formulated and the grinding test was carried out with the steel ball ratio of each scheme. According to the calculation of grinding medium size and ratio and the laboratory grinding comparison test， the optimal grinding medium size and ratio of 3.2 m× 3.1 m lattice ball mill in concentrator is ?70∶?50∶?40∶?30=20∶30∶20∶30.The grain size uniformity of the grinding products in this scheme is the best， the coarse grade yield including +0.2 mm grain size is the lowest， while the intermediate easy grade,-0.2 +0.038 mm grain size yield is the highest，reaching 66.78\mathrm{\%}，while the -0.038 mm grain size content is lower. During the industrial test，ore samples were obtained from the overflow of the 7# and 8# mills on site， and flotation comparison tests were carried out in the laboratory XFD-0.5 mini flotation machine.The industrial test results show that the content of -0.038 mm and -0.074 mm in grinding products increased by 0.47\mathrm{\%}，2.13\mathrm{\%}，and the content of +0.2 mm decreased by 3.14\mathrm{\%} after using the recommended medium scheme.The content of -0.2+0.038 mm in the intermediate easy-to-select grade increased by 2.68\mathrm{\%}，the copper recovery rate increased by 3.70\mathrm{\%}，and the unit ball consumption decreased by 0.032 kg/t.The aim of improving the grain size composition of grinding products， improving the sorting index of copper and reducing the unit consumption of medium in the copper ore processing operation of the concentrator is achieved，and it has certain guiding significance for improving the quality of grinding operations.