The performance of dovetail hydrostatic guideway is closely related to the selected initial oil film thickness.The relationship between the initial oil film thickness and the static and dynamic performances of the closed hydrostatic guide regulated by PM flow controller was analyzed and derived.The results show that increasing the initial oil film thickness of both bottom large surface and dovetail surface can effectively improve the bearing capacity of the guide,but the increase is not significant.Reducing the initial oil film thickness of both bottom large surface and dovetail surface can improve the static stiffness and dynamic stiffness of the dovetail guide.The change in initial oil film thickness on the bottom large surface of the guide has a greater impact on static stiffness,while the change in initial oil film thickness on the dovetail surface has a greater impact on dynamic stiffness.In actual working conditions,an appropriate initial oil film thickness should be selected based on the designed guide operating conditions.