When the highspeed train passes through the tunnel,the external air pressure of the gearbox is lower than the internal air pressure,which will cause the lubricating oil leakage of the gearbox.Aimed at the lubricating oil leakage problem of the gearbox,based on the principle that different impellers rotate with the shaft to stir the air inside the bearing sleeve will form different pressure zones,a set of impeller group sealing structure was designed in the bearing end cover,which can rotate in two directions synchronously with the transmission shaft.The passage model was cut out through threedimensional modeling,and the pressure distribution and velocity distribution in the impeller group channel were simulated and analyzed by the hydrodynamics software.The results show that there is a high pressure region in the middle impeller region and a low pressure region in both sides of the impeller,which can significantly improve the oil leakage of the gearbox.The velocity distribution in the flow channel has no obvious phenomenon of cutoff and eddy current.According to the results of fluid analysis,the relative optimal structural parameters of the impeller group in the sealing structure were explored,which provides a reference for the optimal design of gearbox sealing structure.