A finite element model of gearbox and labyrinth seal structure was established based on ANSA software and the multiphase flow transient simulation analysis was carried out by FLUENT software to solve the lubricating oil leakage problem of a high-speed train gearbox labyrinth seal.The influences of the relative meshing depth,throttle tooth thickness,radial clearance,diameter and number of oil return hole,distance between tooth and step,tooth width and seal clearance on the oil leakage of labyrinth seal structure were studied.The results show that when the relative meshing depth is greater than 0.5,the oil leakage is negatively correlated with the relative meshing depth.The oil leakage is negatively correlated with the throttle tooth thickness,the diameter and number of oil return hole.The oil leakage is positively correlated with radial clearance,tooth width,distance between tooth and step and seal clearance.According to the study results,the labyrinth seal structure was improved,and the oil leakage of the improved labyrinth seal structure was reduced to 3.6% of the original leakage.