The oil film flow state is changed because of the big difference in oil film thickness between deep and shallow pockets of the step hydrodynamic sliding bearing. By using a visualization experiment scheme, the change rules of oil film flow states in the deep and shallow pockets and the their border of the step hydrodynamic sliding bearing were researched by using bubble tracer method, and the effect of bearing velocity and least radius clearance on the oil film flow states was analyzed. The results show that mixed flow states appear at the border between deep and shallow pockets for the sharply altered steps of the step bearing easily resulting in the oil film vortex. The increased bearing velocity will cause the increase of oil film turbulent flow in the deep pocket, and the increased bearing clearance is easy to cause the turbulence phenomenon in the shallow pocket. The trend of experimental data is accordant with the calculation result of the theoretical criterion.