Abstract: Grinding is the main process to realize the dissociation of useful minerals and gangue minerals.Different minerals have different mechanical properties, which require selectivity when grinding.The state of media movement has a decisive influence on the selective grinding of ore, especially when brittle minerals and harder minerals coexist, the adjustment of the media movement state is particularly important.The tin deposits in southwestern are the gathering places of tin resources in our country.The ore contains both brittle mineral cassiterite and harder pyrite and quartz.Aiming at the problem that the cassiterite polymetallic sulfide ore is embedded with fine grain size and brittle minerals are easy to pass through the fans during the grinding process, the choice of ore under different grinding conditions is studied.The research results show that the spherical medium has a strong impact and crushing force on the ore, and it will over-crush the brittle minerals, which is not conducive to the subsequent beneficiation effect.Adding the cylindrical medium can avoid this phenomenon; increase the grinding concentration and keep the mill speed at the low speed are good for selective grinding.Because the low speed of the mill can change the motion state of the medium, reducing the crushing effect, increase the grinding effect of the hard minerals, avoid the production of more fine particles in the grinding.Therefore, in the process of grinding ore containing brittle minerals and a large number of hard mineral symbiotic ore, using sphere medium and column medium grinding ore, reduce grinding speed, appropriately improve the concentration of grinding ore and other measures to improve the stress state of the ore by the grinding medium, can improve the selective grinding effect of the ore.