Divinylbenzene-grafted Ultra-high-molecular-weight polyethylene (UHMWPE) fibers were used to reinforce the Polytetrafluoroethylene (PTFE) composite and the friction and wear behaviors of UHMWPE/PTFE composite were studied on the ring-block machine under vacuum condition. The worn surfaces of specimens were investigated using scanning electron microscopy and energy dispersive spectroscopy (EDS). The results showed that the friction coefficient and temperature of UHMWPE/PTFE composites with surface-treated UHMWPE fiber were apparently lower than that with untreated one. In conclusion, the surface treatment favored the improvement of the higher interface strength and so had good effect on improving the tribological properties of the composites. The dominant wear mechanisms were adhesion wear, plastic deformation, brittle facture, and spalling. The EDS analysis of the worn surface indicated the trend of the tribochemical reaction of the Fe related to the transfer of the PTFE.