Abstract: A numerical method was used to study the characteristics of the adhesion between wheel and rail under oil contamination. A two-dimensional wheel/rail adhesion numerical model considering the surface roughness of wheel and rail under oil contamination was established based on the partial elastohydrodynamic lubrication (EHL) theory. A multigrid method was employed as a numerical tool in finding the characteristics of the adhesion by the proposed model. The contact pressure of the wheel and rail under oil contamination was analyzed. The effects of the train speed and wheel/rail contact pressure on the adhesion between wheel and rail were investigated. Through EHL analysis, the distributions of fluid dynamic pressure and the pressure carried by the solid roughness in the wheel/rail contact were obtained. The results show that the adhesion coefficient decreases and gradually approaches to a constant with the increase of train speed. It is also shown that the adhesion coefficient increases with the increase of wheel/rail contact pressure.