To discuss the effect of base oils on the rheological property of lithium greases,the rheological parameters of lithium greases prepared with different viscosity of base oils were studied in a steady shear flow and a slight oscillation shear flow.By analyzing rheological parameters such as the thixotropy,yield stress and apparent viscosity,storage modulus and strain amplitude,the influences of viscosity of base oils on the rheological property of lithium greases were discussed.The results indicate that,with the decreasing of viscosity of base oils,the viscoelasticity of lithium greases is more significant,the energy required to destroy the structure of lithium greases is much greater,and their structures are more stable.