Hydrostatic center rack is an open type hydrostatic supporting equipment. In this paper, taking oil film of middle pillow of hydrostatic center rack as the research object, the velocity field, pressure field and dynamic pressure effect are simulated based on CFX finite element analysis software. The velocity distribution, pressure field and the relationship curve between spindle speeds and dynamic pressure are obtained. The simulation results show that there is negative pressure at the entrance of spindle rotation direction. When the spindle speed is less than 360r/min, the dynamic pressure effect is not obvious and at the steady state basically. Above this speed, the dynamic pressure effect increases significantly as the spindle speed rises. The simulation results can reflect the flow law of internal flow field of the middle pillow. It provides a theoretical basis for the structure optimization of hydrostatic center rack and open type radial sliding bearing in engineering practice.