Wear is a dynamic process in which a large amount of materialsare continuously lost from the working surface due to themechanical interaction between a tribopair in frictional slidingcontact. The wear of engineering components in most cases is acritical factor that influences the product’s life and even its per-formance [1]. Brass–steel tribopair is commonly used in engi-neering components [2–4], particularly in the sliding bearings[5,6]. In general, a hydrodynamic sliding bearing is worked inhydrodynamic lubrication. The contact surfaces are completelyseparated by oil film, the loads are supported by the lubricating oiland there is almost no wear on the surface of bearing. However,during the starting and stopping process of a machine, the lubri-cation film is thin due to the low speed, and there is direct contactbetween the asperities of surfaces, which leads to significantdeformation and abrasion of the material. In this case, hydro-dynamic lubrication has not been established, and the tribopairworks under a mixed lubrication condition [7]. This phenomenonoccurs more commonly for equipments that are started frequently,such as the main-shaft bearing of machine tools and elevators. Thefailure at the majority of the sliding bearing is the surface invali-dation that is caused by wear [8]. In this study, we mainly studythe worn surface of a brass–steel pair during the wear process inmixed lubrication conditions