In order to study the influence of water pollution on the lubricating performance of lubricating oil,through the point contact light interference test,the profiles of film thickness and the interferogram pattern under three lubrication conditions of fully flooded condition,slight oil starvation and severe oil starvation were obtained,and the influence of free water on the lubrication performance of the oil in the contact area was studied.The results show that,under fully flooded condition,free water has little effect on the film thickness of the point contact,which mainly affects the central film thickness.Under the condition of oil starvation,free water has an advantage effect on the film thickness of the point contact.However,under three lubrication conditions,the boundary of the cavitation zone becomes blurred and elastohydrodynamic lubrication performance of oil lubricant is enhanced due to the free water.