The work aims to develop new lubricant additives with excellent properties in perfluoropolyether (PFPE) base oil by studying the modification of perfluoropolyether derivatives. The perfluoropolyether alcohol was modified to obtain a novel perfluoropolyether derivative, named as perfluoropolyether pentafluorobenzoate. The chemical structure of perfluoropolyether pentafluorobenzoate was characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy, and the compatibility with PFPE was also tested. The tribological performance as additive in PFPE base oil was tested by four-ball friction tester. The surface composition and morphology were analyzed by X-ray photoelectron spectroscopy (XPS), energy dispersive spectrometer (EDS), 3D profiler and scanning electron microscope (SEM), and the relevant lubrication mechanism was also explored. The new perfluoropolyether derivatives synthesized had good thermal stability and began to decompose at 150 ℃. Compared with base oil, the additive could reduce friction coefficient by 25% and wear spot diameter by 30%, and had better tribological properties than other additives. When mass fraction was 2%, the friction coefficient decreased to 0.073 and the wear spot diameter was 0.303 mm. This additive could promote the formation of more free fluorine atoms by the breaking of the carbon-fluorine bonds and further boosted the tribochemical reaction on the mental surface, while pentafluorobenzene bound by ester groups would be adsorbed firmly. Both of additives worked together on the metal surface to form a strong lubrication film, thus achieving better anti-friction and anti-wear performance. This modified perfluoropolyether derivative is a novel additive suitable for PFPE base oil with excellent tribological performance.