In this work, the effect of thermal, mechanical, and tribological properties of the blending system of different contents of short carbon fibers (SCFs) on different-viscosity poly-ether-ether-ketone (PEEK) was reported. The composites were manufactured using injection molding technique. Mechanical and tribological properties were measured by the tensile strength, the flexural strength, the coefficient of friction, and the wear rate. The results showed that the wear resistance and mechanical properties of the PEEK with the lower viscosity appeared on a more outstanding level, and experimental results showed that PEEK composites with added 10 wt% SCFs were optimal about the tribological behaviors and mechanical properties of the composites. Furthermore, based on scanning electron microscope inspections, the situation of the friction and worn surface of the material was explained.