Development of novel green lubricants that meet low viscosity and effective anti-wear requirements is a tireless pursuit to improve fuel economy and reduce exhaust emissions, as well as enhance reliability. Herein a series of hydrophobic deep eutectic solvents (HDESs) with ultra-low viscosity were successfully synthesized by combining eco-friendly economical DL-menthol (DL) with fatty acids of various alkyl chain lengths. According to quantum chemistry method, weak hydrogen bond interaction between DL and fatty acid was calculated. The as-prepared DL-based HDESs lubricants present prominent physicochemical properties and lubrication functions. Thereinto, DL+Dodecanoic acid HDES with a low viscosity of 8.73 mm2 /s (40 ◦C) achieves a 23.05 % reduction in friction and a 44.22 % reduction in wear compared to the PEG 200 base oil at 491N. According to experimental characterizations and ffrst-principles calculations to reveal their anti-wear mechanism, the excellent wetting and ultra-low viscosity of the HDESs ffuid facilitates rapid physisorption and chemisorption. Meanwhile, the absorbed fflm contributes to the formation of the long alkyl chains ffow layer and the tribo-chemical fflm composed of hydrocarbon (CxHy), oxy hydrocarbon (CxHyOz) fragments and iron oxide/hydroxide-rich layer, which endows HDESs with excellent lubrication properties. This founding furnishes a new strategy to design green low-viscosity and high-performance anti-wear HDESs lubricants in sustainable lubrication applications.