<p>8Cr4Mo4V bearing steel has been widely used in the industrial applications due to its exceptional mechanical properties. To further improve the tribological properties, the microstructure of 8Cr4Mo4V bearing steel was controled through varying the austempering time in this work. The microstructure, hardness, and tribological behaviors were systematically investigated. The results show that 8Cr4Mo4V steel is mainly composed of martensite, bainite, and retained austenite after quenching and austempering treatment. With increasing the austempering time from 1 h to 8 h, the proportion of bainite increases gradually while martensite decreases correspondingly. The hardness decreases from 881 HV to 737 HV with the decrement of 16.34%. However, the wear rate increases firstly and then decreases, reaching the lowest wear rate of 0.43×10⁻⁷ g(N·m)⁻¹ for the 8 h austempered sample. The wear mechanism transitions from dominant abrasive wear to surface plastic deformation, correlated with the microstructure evolution. 8Cr4Mo4V steel austempered for 8 h demonstrates optimal tribological properties attributed to bainite-dominated microstructure.</p>