The properties of ultra-high molecular weight polyethylene (UHMWPE) fibers reinforced epoxy resin composites were studied and the effects of the fiber surface treatment were investigated. The results showed that the surface treatment increased the roughness, O-containing groups (especially -OH groups), crystallinity and improved the wettability of UHMWPE fibers. The impact strength of the treated UHMWPE fibers/epoxy composites reached the maximum of 92.6 kJ/m2, which was higher than that of pure epoxy and as-received fiber composites. The tensile strength of both as-received and treated fiber composites showed lower than the pure epoxy. However, the tensile modulus was observably increased. The bending strength and modulus of the treated UHMWPE fibers/epoxy composites were 26.2 % and 26.0 %, higher than those of pure epoxy, respectively. The friction coefficients of the two types of composites were both increased. The dynamic mechanical analysis (DMA) results showed that Tg shifted toward higher temperatures and the reduction of tan δ peak of the treated UHMWPE fibers/epoxy composites indicated the adhesion of treated fiber with resin matrix was better than that of as-received fibers, which was in accord with the scanning electron microscope (SEM) analysis. The adding of the treated UHMWPE fibers to the epoxy matrix offered a stabilizing effect against the decomposition.