Polyetheretherketone (PEEK)-matrix nanocomposites filled with copper nanowires (Cu NWs) and copper nanoparticles (Cu NPs) were prepared by hot compaction method. The effects of Cu NWs and Cu NPs on the thermal conductivity, dynamic mechanical performance, and tribological property of PEEK-matrix nanocomposites were investigated. Results indicate that Cu NPs and Cu NWs with different geometry exhibit different influences on the crystallization behavior, melting behavior, dynamic mechanical properties, and friction and wear behavior of PEEK matrix. Namely, Compared to Cu NPs, Cu NWs can more efficiently better dissipate heat and transfer stress at PEEK/nanofiller interface. Moreover, the friction and wear behavior of the PEEK-matrix nanocomposites is also related to the geometry of the Cu nanofillers to some extent. This is because Cu NPs can act as roll bearings to reduce friction; and Cu NWs with a high thermal conductivity can prevent softening of PEEK matrix and increase the wear resistance via well dissipating friction heat away from the sliding interface. In one word, the comprehensive properties of PEEK-matrix nanocomposites are closely related to the geometry effect of Cu NPs and Cu NWs, which could be of significance for revealing the relation between the micro morphology and the macro application of inorganic nanofillers.