Hydrostatic thrust bearing lubrication is significantly affected by the oil flow state of gap oil film, but it can not be measured by experiment and analysis. For this problem, the oil flow state of gap oil film in sector cavity multi-pad hydrostatic thrust bearing during rotation was simulated by using computational fluid dynamics, lubricating theory, and Finite Element Method. Laminar model and κ-ε turbulence model were adopted to model incompressible steady equations, and the equations were discreted by using Finite Volume Method and Second-order Finite Difference. By comparing the calculated results of numerical simulation and semi-empirical theoretical equation, the numerical simulation is proved feasible in oil film state analysis parameter prediction, which can overcome the deficiency of single model and get good effect. Streamlines and velocity vectors show that the lubricating oil flow in the resistive oil edges and oil cavities are laminar flow under the conditions of speed and flow in less than a certain value, while the flow and speed are more than a certain value, the lubricating oil flow in the resistive oil edges is also laminar flow, but the lubricating oil flow in the oil cavities is turbulent flow, then determines critical flow and critical speed. The critical flow and critical speed were determined, it provides a theoretical basis of the temperature field and thermal field deformation calculation.