Abstract: The multi-walled carbon nanotubes (CNTs) functionalized with maleimide and carbon fibers (CF) were mixed and treated with CeCl₃ to obtain CNTs-CF multi-scale reinforcement. These reinforcements were characterized by FTIR, XPS and SEM. The CNTs-CF/epoxy (EP) composite was prepared by the molding method with EP as the matrix. The mechanical properties and fracture morphology of CNTs-CF/EP composite were analyzed to explore the influence of CNTs-CF multi-scale reinforcement on the interfacial properties of EP composite. The results show that the modified CNTs can be chemically grafted on the CF surface through the bridging effect of rare earth Ce to solve the problems of weak interface bonding between CF and resin matrix and CNTs not easy to disperse, effectively improving the interfacial performance between the reinforcement and matrix. Therefore, the tensile strength and Young’s modulus of CNTs-CF/EP composite are increased by 36.76% and 71.57% relative to those of CF/EP composite, respectively; 24.79% and 52.17% relative to those of CF modified by CeCl₃ (RECF)/EP composite, respectively. The chemical grafting method of rare earth Ce is successfully used to prepare CNTs-CF multi-scale reinforcement, which provides a new environment-friendly method for obtaining advanced lightweight resin matrix composites.