Abstract: The behavior of the aerodynamic journal bearing is studied by numerically simulating the steady state non linear Reynolds equation. The finite difference method is used to solved the Reynolds equation with successive over relaxation (SOR)method in MATLAB programming. The film pressure distribution and film thickness distribution are obtained. Then the influences of some parameters, such as radius gap, rotating speed, width diameter ratio and eccentricity, on the maximum of film pressure are researched and the relationship obtained may be used to design this type of journal bearings.