Abstract: To further optimize the design of the hydrostatic bearing system,a finite element model for the oil film of hydrostatic bearing is established by applying the CFD simulation software CFD-ACE+ based on engineering practice,and the numerical simulation is carried out under fluctuation load.According to the results,the characteristics of the bearing capacity and stiffness of the oil film under fluctuation load are analyzed compared with the theoretical formula,and so is the influence of the supply velocity on the characteristics.Results indicate that the thickness and bearing capacity of the oil film response to the load in a certain delay,which is affected by the inlet velocity because of inertia,the relationship between the film bearing capacity and the thickness does not coincide when the load increases and decreases,and the stiffness is the most unstable when the load reaches the maximum and minimum.