Bearing chamber is one of important components that support aero-engine rotors and research on oil droplet and oil film motions is an important part of bearing chamber lubrication and heat transfer design. Considering the pressure of sealing air is an important operating condition that affects the oil droplet and oil film motions,the effect of sealing air pressure on airflow in bearing chamber is investigated in this paper firstly; and then based on the air velocity and air / wall shear force,the oil droplet moving in core air,deposition of oil droplet impact on wall as well as velocity and thickness of oil film are analyzed secondly; the effect of sealing air pressure on oil droplet velocity and trajectory,deposition mass and momentum,as well as oil film velocity and thickness is discussed. The work presented in this paper is conducive to expose the oil / air two phase lubrication mechanism and has certain reference value to guide design of secondary air / oil system. Bearing chamber is one of important components that support aero-engine rotors and research on oil droplet and oil film motions is an important part of bearing chamber lubrication and heat transfer design. Consider the pressure of sealing air is an important operating condition that affects the oil droplet and oil film motions, the effect of sealing air pressure on airflow in bearing chamber is investigated in this paper first; and then based on the air velocity and air / wall shear force, the oil droplet moving in core air, deposition of oil droplet impact on wall as well as velocity and thickness of oil film are analyzed secondly; the effect of sealing air pressure on oil droplet velocity and trajectory, deposition mass and momentum, as well as oil film velocity and thickness is discussed. The work presented in this paper is conducive to expose the oil / air two phase lubrication mechanism and has certain reference value to guide design of secondary air / oil system.