Abstract: Aiming at the problem of poor grindability of a company's mixed materials and high power consumption of the open circuit cement mill combined grinding system, technical measures were taken to increase the ball diameter of the first chamber, increase the grinding area of the second chamber and the third chamber of the ball mill, and replace the self-cleaning grate plate of the replaceable screen plate. The cement output of P·O42.5 increased from 98t/h to 127t/h, and the power consumption of the system decreased from 33.0kW·h/t to 28.3kW·h/t. The effect of increasing production and saving electricity was remarkable.