Abstract: The vector method of the gear engagement theory is used to describe the manufacturing and meshing process of the spiral bevel gears in the aeroengine.The geometry and kinematic parameters of each contact point are considered,including the position,the curvature and the speed of each contact point on the tooth surface.The load on tooth in each contact position is determined with the help of Loaded Tooth Contact Analysis (LT CA) and the thickness of oil film on each contact position is obtained as theoretical foundation for judging the lubrication state.Meanwhile,300 hours test of the gears has been made and the topographical feature of the tooth surface by means of scanning electron microscope is investigated.The results of calculation and experiment show that the gears are under boundary lubrication and partial elasto-hydrodynamic lubrication.