Abstract: Polyether ether ketone (PEEK) has good mechanical properties. However, its high viscosity when molten limits its use because it is hard to process. PEEK nanocomposites containing both carbon nanotubes (CNTs) and polyether imide (PEI) were prepared by a direct wet powder blending method using a vertical injection molding machine. The addition of an optimum amount of PEI lowered the viscosity of the molten PEEK by approximately 50% while producing an increase in the toughness of the nanocomposites, whose strain to failure increased by 129%, and fracture energy increased by 97%. The uniformly dispersed CNT/PEI powder reduced the processing difficulty of PEEK nanocomposites without affecting the thermal resistance. This improvement of the strength and viscosity of PEEK facilitate its use in the preparation of thermoplastic composites.