The effects of water contamination of lubricants on thermal elastohydrodynamic lubrication of journal bearings of water turbo generator were studied.The relationships of viscosity,mass concentration of water and temperature of the oil emulsion were determined with experimental measurements.The lubrication performance of journal bearing with different water concentration was investigated,the orbit of shaft center from initial position to equilibrium position was analyzed,and many lubrication parameters at equilibrium position were studied,including hydrodynamic pressure and maximum hydrodynamic pressure,film thickness and minimum film thickness and temperature.The results show that the viscosity of water in oil emulsion is increased obviously with increasing water mass concentration,and its density,specific heat and thermal conductivity are also increased,but their changes are not large.For the comprehensive effects of various factors,the bearing load capacity is enhanced,and the film thickness,temperature and minimum film thickness are increased,and the maximum film pressure is dropped.