An unprecedented electrostatic self-assembly of MXene and SiO 2 on carbon fiber (CF) to enhance the interfacial properties of CF-reinforced epoxy resin composites is disclosed. MXene with negative charge was anchored on the cationized CF surface via a strong electrostatic interaction, followed by synergistic effect of amine-modified SiO 2 (positive charge) to furnish a stable MXene/SiO 2 material with three-dimensional structure, which takes the advantages of high modulus, large specific surface area, and high-surface activity. The involvement of the two nano-materials with different dimensions and morphologies results in synergistic enhancement on mechanical interlocking, leading to excellent chemical bonding connection between CF and resin, which could transfer stress and dissipate energy effectively. Moreover, the surface energy of CF increased from 26.67 to 48.12 mJ/m 2 after assembly of MXene/SiO 2 . Compared with unsized CF/EP composites, the interfacial shear strength, interlaminar shear strength, and flexural strength of CF/MXene/SiO 2 /epoxy (EP) composites were increased by 73.2%, 61.2%, and 39.2%, respectively. Dynamic mechanical analysis poxy (DMA) tests showed that the storage modulus of the CF/MXene/SiO 2 /EP composites was enhanced by 64% compared with CF/EP composites, and the glass-transition temperature of composites was elevated from 147.9 to 151.8 C. This protocol provides a promising strategy for designing advanced CF/EP composites with threedimensional structure.