Abstract: Specific to the stress concentration at the edges of straight generatrix shape roller in cylindrical roller bearing, the method of geometric modification on roller was used. The forces acting on a roller and the relative motion for the bearing were carried out with the quasi-dynamic analysis method. By considering the contact conditions, roller modification parameters and real surface roughness, a mixed lubrication model was established. The effect of different roller modification parameters and speeds on the lubrication performance of bearing were calculated. The results from the judgement of lubrication show that both the roller convexity and roller round corner radius at roller ends, δ and r, having the optimized range to make the maximum oil film pressure and subsurface maximum von Mises stress (σ) decreased significantly, and weakened the edge effect. The δ and r had insignificant effect on average film thickness at center (h_c) and friction coefficient (f). With an increase rotation speed of the bearing, the h_c increased while the f and σ decreased, and the effect of the rotational speed on the δ of modified roller appeared to be significant in the mixed lubrication status. Compared to the roller without modification, roller with modification showed better lubrication performance.