With the introduction of national energy conservation and emission reduction policies, the improvement of energy efficiency of cement grinding system has become particularly urgent. The conventional cement roller press combined/semi-final grinding process technology has some technical problems, such as incompatibility between materials and systems, mismatch between systems and equipment, and lack of adjustability. In view of this, energy-saving and low-carbon technologies such as online adjustable flexible grinding process based on the coupling concept of "material system equipment" and high-efficiency powder selection equipment with side inlet air with settling chamber have been innovatively developed, and have been successfully applied to many industrial projects. Industrial application practice shows that the cement roller press combined grinding system with "large roller press+small ball mill" can significantly increase the system output, reduce the process power consumption and ensure the performance of cement products under the operation mode of "ultra-low resistance, ultra-low air volume and ultra-high concentration”. Compared with the national first-class energy consumption quota standard, the average power saving per ton of cement is as high as 5.1kW·h, which has reached the international leading level, providing strong support for the cement industry to achieve the goal of carbon peak and carbon neutralization.