Three types of surface modifiers, N-β-aminoethyl-y[1]-aminopropyltrimethoxysilane coupling agent (SGS), a mixture of silane and rare earth elements (SGS/RES), and rare earth elements surface modifier (RES), were used to treat the glass fiber surface. Tensile tests of glass fiber–reinforced polytetrafluoroethylene (GF/PTFE) composites with different surface treatment conditions, surface modifiers, and glass fiber content were carried out. Finally, the fracture surface morphologies of GF/PTFE composites were investigated using scanning electron microscopy. Experimental results showthat the tensile properties of the treated GF/PTFE composite increased compared with those of the untreated one. RES is superior to SGS/RES and SGS modifiers in promoting interfacial adhesion between the glass fiber and PTFE because of the effects of rare earth elements on the compatibility. Meanwhile, the optimum contents of rare earth elements for the improvement of the tensile properties of GF/PTFE composite were obtained for RES and SGS/RES modifiers. The interfacial adhesion of the GF/ PTFE composites treated with RES or SGS/RES modifiers was mainly controlled by the contents of rare earth elements. The tensile properties of the GF/PTFE composites improved considerably when the content of rare earth elements in surface modifiers was 0.2-0.4wt%, and the optimumtensile performance of GF/PTFE composites was obtained at 0.3wt% RE content.