In this paper, the surface of nano-lanthanum oxide was modified, and the different surface characteristics of modified nano-lanthanum oxide were analyzed. Meanwhile, the influence of surface modification on the tribological and mechanical properties of polytetrafluoroethylene nanocomposites was investigated. Results indicate that the tribological properties, degradation temperature, notched impact and tensile strength of polytetrafluoroethylene nanocomposites filled with modified nano-lanthanum oxide can be increased simultaneously. A uniform transfer film can be observed on the counterpart surface. Results also show that the smaller the difference of surface energy between filler and matrix is, the higher wear resistance and mechanical properties the polymer nanocomposites will have.