Based on the basic theory of hydrodynamic lubrication,the mathematical model of hybrid hydrodynamic lubrication of journal bearing was established by using the numerical calculation method in MATLAB software.The influence of different water content in the lubricating oil on the lubrication performance of radial sliding bearing was compared and analyzed.The results show that the minimum film thickness and pressure are decreased with the increase of water content,and the maximum film pressure is increased with the increase of water content.A small amount of water in the lubricating oil makes the film force and friction force become larger,which is not conducive to the dynamic lubrication of the bearing,so the lubrication performance of the bearing becomes worse,and the friction and wear of the bearing is increased,and the service life of the radial sliding bearing is reduced.