The work aims to study the preparation method of Flaky nano-MoS2 and its tribological applications in oil lubrication. Flaky nano-MoS2 was prepared by hydrothermal reaction at 220 ℃ with sodium molybdate and thiourea as raw materials. The chemical compositions, crystal structure and other physicochemical properties of the nano-sheets were characterized by FT-IR, XRD, HRTEM and EDS, respectively. After the surface was coated and modified by silane coupling agent (KH570), KH-MoS2 was dispersed into the paraffin oil through ultrasonic treatment to form the lubrication oil disperse system. Further, the tribological properties of nano-sheets in the composite lubrication oil as additives were tested on a ball-on-disk tribometer. The theoretical model was established according to the results of SEM, EDS, etc. And the tribological properties were investigated. The flaky nano-MoS2 with the sizes of 30~100 nm was prepared. The tribological performance of paraffin oil could be significantly improved after the surface-coated MoS2 was added. When the additive amount of MoS2 was 1.0 wt%, the coefficient of friction (COF) was 53.4% lower than that of pure paraffin oil and the diameter of the wear tracks was 41.1% less than that of pure paraffin oil. Besides, obvious furrows could be observed on the surface of the disk when pure paraffin oil was used as lubricant. The width of wear track with nano-oil as lubricant decreased by 43.9% to the maximum extent. KH-MoS2 can flow into the frictional contact interface along with the lubricant and form a deposited film on the contact region by being attached to the friction surface as the interface slides relatively to achieve excellent friction-reducing and wear-resisting effect.