Abstract: In response to the urgent demand for lightweight and efficient electromagnetic shielding materials in cross-sea aircraft, a superhydrophobic carbon fiber composite with excellent electromagnetic shielding performance and environmental durability has been developed. Using carbon fiber reinforced polymer (CFRP) as the structural substrate, a layer-by-layer functionalization strategy was employed to construct MXene conductive layers and a polydimethylsiloxane (PDMS) and nanoparticle composite superhydrophobic protective layer, forming a CFRP-MXene-PDMS multilayer structure. Performance tests demonstrated that the introduction of the PDMS layer resulted in a material surface contact angle of 164°, achieving superhydrophobicity, which effectively blocked the penetration of environmental moisture and oxygen, providing crucial protection for the MXene conductive layer. This protection enabled the material to maintain excellent electromagnetic shielding performance after accelerated environmental aging, with the shielding effectiveness attenuation rate controlled within 15%. Simultaneously, the introduced nanoparticles synergized with PDMS to form a stable micro-nano hierarchical architecture, which substantially strengthened the interfacial adhesion between functional layers and the substrate. This structural enhancement effectively improved the composite's quasi-static tensile performance and contributed to the overall structural integrity. This study, through an integrated "conductive-protective" material design approach, innovatively utilizes a superhydrophobic layer to address the environmental stability challenges of MXene, providing a new technical pathway and theoretical support for the development of lightweight, long-life electromagnetic shielding materials suitable for long-endurance cross-sea aircraft.