Numerical simulation of oil film Characteristics of a crankshaft bearing for gasoline engines was completed based on Navier-Stokes equations. Through 3-D simulation, the distributions of pressure and component inside the oil film in different journal rotation speeds was obtained, and the effect of the crankshaft rotation speed on the characteristic of oil film was uncovered. The results are shown as following. The action range of load bearing area of the journal bearing oil film and the location of the max oil film pressure do not change with the increase of the rotation speed of crankshaft. As the rotation speed of crankshaft increases, the pressure of oil film increases linearly in the same circumferential location, and it increases fastest in the place of max oil film pressure. In addition, with the increase of the rotation speed of crankshaft, the area filled with air in the breaking up area of oil film declines, and the breaking up area near the oil inlet rises.