A new series of functionalized ionic liquids containing ester-group were synthesized through a typical two-step way. The physicochemical properties of the functionalized ionic liquids were studied and the tribological properties of them as lubricants for steel-steel contact were evaluated on an SRV friction and wear tester and compared with the perfluoroalkylpolyether (PFPE), a low-volatility and fluorine containing lubricant, and a conventional ionic liquid, 1-butyl-3-methy imidazolium tetrafluoroborate (LB104), which is nonfunctionalized. Results showed that all the ionic liquids studied in this paper have better lubricities than PFPE as lubricants for steel-steel friction pairs. Functionalized ionic liquids show worse friction reducing abilities at relatively lower loads, which could be ascribed to their higher viscosities, but they always exhibit better anti-wear abilities than LB104. The possible friction mechanisms were discussed.