Abstract: In this work, a new kind of functionalized ionic liquid (IL) containing ester-group, 1-ethoxycarbonylmethyl benzotrizaole terafluoroborate, was synthesized through a typical two-step way and characterized by Fourier Transform infrared spectroscopy. Tribological experiments were performed on a four-ball friction and wear tester with as-prepared IL lubricant mixtures, and compared with neat sunflower oil. The morphologies and main elements of the worn surfaces were observed and evaluated by optical microscopy, scanning electron microscope(SEM)and X-ray photoelectron spectroscopy(XPS). The results show that the prepared IL possessed excellent friction-reducing and anti-wear properties. When the addition concentration was 1.5%, the friction coefficient and the wear scar diameter were both smallest, and decreased by 42.9% and 33.3%, respectively, as compared to the base oil without ionic liquid. XPS results demonstrate that a protective triblo-film was formed on the contact surface during friction progress.