The film forming ability of the watersoluble thickener is an important indicator to measure its lubricating performance.To study the film forming properties of the watersoluble thickener,watersoluble thickener polyoxyethylene (PEO) was selected as the test material.Rheometer was used to conduct rheological tests on different content of PEO aqueous solution at different temperatures.The selfmade point contact elastohydrodynamic lubrication test bench was used to study the film forming ability of different content of PEO aqueous solution.The results show that the PEO aqueous solution exhibits shear thinning property of nonNewtonian fluid.With the increase of PEO content,the nonNewtonian effect of PEO aqueous solution is increased.The lubrication behavior of the PEO aqueous solution at higher entrainment velocity conforms to the elastohydrodynamic lubrication(EHL) theory,while that at lower entrainment velocity conforms to the thin film lubrication (TFL) theory.There is different critical speed of transition from TFL to EHL for the different content of PEO aqueous solution,the higher the PEO content in the aqueous solution,the higher the critical speed.For the same content of PEO aqueous solution,the greater the load,the smaller the film thickness.Under the same load,the higher the PEO content in the aqueous solution,the greater the film thickness at the center of the lubricating film.