To explore the effect of graphene oxide(GO) additives on the film forming characteristics of the base oil under different lubricating conditions,the thickness,layer number and functional group of GO were characterized by atomic force microscopy(AFM) and fourier transform infrared spectroscopy(FTIR),and the effects of GO additive on the film forming characteristics of polyalphaolefins(PAO10) and polyalkylene glycol(PAG) base oils under elastohydrodynamic lubrication and mixed lubrication conditions were studied on a ball-disk optical interferometer.The results show that GO has little effect on the film forming ability of PAO10 and PAG under the state of elastohydrodynamic lubrication,and there is little difference of the minimum film thickness of base oil before and after adding GO.Under the state of mixed lubrication,the addition of GO can increase the minimum film thickness of the base oil PAO10 and effectively slow down starvation conditions in the contact zone.But GO has little effect on the film forming characteristics of the base oil PAG.