Aiming at a kind of floating plate structure which was suitable for highpressured and largeflowed electrohydrostatic servo motor pump, FLUENT software was used to simulate liquid film’s threedimensional flow of connecting sleeve’s platetype friction pair with a laminar flow model. The liquid film flow distribution (such as pressure and velocity) was gotten. The effects of different connecting sleeve’s outside diameters on film open force were researched. The balance factor range of the connecting sleeve’s platetype friction pair was identified.All of these provide reference for further design of the floating plate structure.