The effect of surface microstructure of specimen on hydrodynamic pressure oil film thickness was studied by adopting the combination of experimental method and numerical simulation method.With the aid of a specially constructed rotor test rig,a contrast experiment was conducted for the specimen with electrochemical finishing process and the ordinary grinding specimen,and the dynamic pressure oil film thickness formed on both of the test specimens in sliding bearing system was measured by applying the optical fiber displacement sensor.The oil film pressure of the test specimens was simulated by adopting the fluid dynamic solution tool of Fluent and the related data were analyzed.Results show that a dynamic pressure oil film with a higher thickness can be formed on the “arc” shaped embossment microstructure which is mold on the surface of test specimen after electrochemical machining,and greater oil film pressure can be generated by a large number of random distributed “arc ” shaped micro modelling structure.The rotate speed has no influence on the maximum and minimum location of oil film thickness.