Abstract: Mixed contact fixed abrasive processing was proposed in this paper for controlling the grinding depth of a definitive tool and decreasing the tool switches frequency for the first time. Thus the machining efficiency can be significantly improved. The transient isotherm hydrodynamic lubrication equations of the liquid membrane between the tool and workpiece were established. Then explicit difference algorithm was adopted. The numerical simulation was conducted to analyze the hydrodynamic pressure and its distribution. The feasibility of controlling the grinding depth by the liquid membrane's hydrodynamic pressure was confirmed by the results. Because the hydrodynamic pressure increases with decreasing maximum grinding depth and its distribution becomes flat. The hydrodynamic pressure obviously increases with the inlet pressure, while its distribution becomes uneven. The influence of the rotational speed is inconspicuous, because of the grinding tool surface topography and the processing quality demand.