Excellent lubrication performance of graphene lubricant is mostly attributed to the dispersion of graphene and forming of tribo-film. Herein, diethylene glycol dodecyl ether (E2C12) functionalized graphene oxide (E2C12-GO) was successfully prepared by simple esterification. The physicochemical properties of as-prepared samples were characterized by a series of characterization methods. E2C12-GO with flat edge and high-level spacing possesses high dispersion stability in PAO 20 base oil. Compared with base oil, 0.08 wt% E2C12-GO could achieve the reduction of average friction coefficient and wear rate by 30 % and 57 % at 150 N, respectively. Even with each long-term friction, E2C12-GO could still maintain the state of robust low friction coefficient. Meanwhile, the addition of E2C12-GO can significantly improve the load-bearing capacity (PB value and PD value) of base oil. The excellent tribological properties of E2C12-GO were attributed to high dispersion and high layer spacing, as well as the reorganization of sliding interface. Prospectively, the E2C12-GO shows promising potential as a multi-functional oil-based lubricating additive in industrial applications.