The work aims to study the effect of water presence in oil on the tribological properties of oil film bearing. The oil film bearing of rolling mill as the object of study was established by mathematic model of oil-water two-phase flow and equation of elastohydrodynamic lubrication under isothermal conditions, so as to study the lubrication properties of oil film bearing in rolling mill, and the variation relationship betwwen pressure & film thickness of oil-water two-phase fluid lubrication film and water content, slip ratio, journal gap, spindle speed, rolling force. With the increase of water content after charging lubricating water, viscosity of the oil-water two-phase flow first increased and reached a maximum (0.08 Pa·s) at a water content of about 30%, then decreased rapidly until reducing to viscosity of pure water (0.001 Pa·s). Dimensionless film thickness reached the maximum (0.82) at waster content of 30% and the minimum (0.68) at 90%. As water content increased, the oil-water two-phase fluid transformed into oil-in-water flow pattern from water-in-oil flow pattern with minor pressure change, film thickness first increased and then decreased. Compared with oil-in-water flow pattern, water-in-oil flow pattern as a lubricant provided better lubricating performance and optimal performance at transition point of flow pattern. With the increase of slip ratio and spindle speed of oil film bearing, pressure and carrying capacity decrease while film thickness and lubrication performance increase. With the increase of journal gap and external rolling force, pressure and carrying capacity increase while film thickness and lubricating performance decrease.