A new oil lubricating and water cooling system of classifier bearing was designed to solve the problem that it is quite difficult to lubricate and cool classifier bearing. The systemic structure and working principle were analyzed based on the overall structure of system, cooling, temperature detecting, lubricating, sealing and so on. A physicalmodel and boundary conditions were established through convection heat transfer theory, then use FLUENT to complete a convective heat transfer analysis, the result shows that the cooling effect of new system is better than conventional system, it could cool bearing down rapiddly and meet the cooling demand of modern largescale Classifier bearing.