In the process of industrial field lubrication management, the main gear box of large-scale mechanical equipment mainly has the pollution problem of nano-particles and micron particles, which often causes severe wear on the tooth surface. Therefore, it is of great value to study the effects of nano and micron SiO2 particles on the tribological properties of industrial gear oil and the actual wear of gear boxes. In this paper, five typical sizes of nano and micron SiO2 particles were selected, and then they were added to new industrial gear oil according to 6 concentrations. Thereafter, the kinematic viscosity, load-carrying capacity, and friction coefficient of oil samples were tested. And the wear scar diameter, wear scar micromorphology, and wear scar surface element of the steel balls were also tested. The specific effects of particle size and concentration on the tribological performance of industrial gear oil were obtained by comparing the test results of SiO2 particle oil samples with the new gear oil. Finally, the lubrication mechanisms of SiO2 particles in four-ball friction pairs and gear friction pairs were derived. The research proves that nano and micron SiO2 particles can affect the establishment of oil film or the formation of chemical film in the friction pair, thus aggravating the actual wear of industrial gear boxes.