Abstract： Three types of structural flow passages were designed, and flow field characteristics of hydrodynamic polishing base plates in different structure flow passages were studied. A mathematical model of flow field with constraint condition were built based on the liquid dynamic theory, and Matlab was used to compare and analyze the distributions of liquid dynamic pressure at different structural parameters. Relationships between buoyancy and film thickness, pressure distribution, structural parameters were obtained. Fluent software was used to calculate the pressure and speed distribution of flow fields. Theoretical and numerical results show that the largest buoyancy is produced by the parabolic structure flow passage，followed by the wedge structure flow passage, while the L structure flow passage is produces the smallest buoyancy. The flow velocity is relatively stable in the area where the workpiece is adhered, providing good condition for noncontact polishing process.