Based on the multiphase flow k-ε model of CFD numerical method,the sealing performance of a new waterproof seal structure for rolling mill bearing was simulated by using the FLUENT software.The cause of sealing failure was analyzed,and the influences of the wear of waterproof seal felt,the rotating speed,the throttling gap on waterproof sealing effect were studied.The results show that the waterproof effect of the new waterproof seal structure can be improved by reducing the wear of waterproof seal felt,increasing the rotational speed and reducing the throttling gap.In order to improve the waterproofing performance of the new waterproof seal structure,the schemes of adding a sealing ring at the gap outlet and transforming the outlet of the exhausting water into a groove structure were proposed.The results show that the sealing ring added at the gap outlet can play a role of waterproofing,but the effect is not obvious.The water discharge at the gap outlet under the same conditions is reduced and the waterproofing effect is greatly improved after transforming the outlet of the exhausting water into a groove structure.