Abstract: In the microelectronic era, electromagnetic pollution is intensifying, while aerospace, new energy, and high-end equipment impose high-temperature bearing-electromagnetic shielding composite requirements. Traditional materials fail to meet both, so there is an urgent need to develop structure-function integrated high-temperature resistant thermosetting composites with excellent mechanical properties and efficient electromagnetic shielding effectiveness.In this study, unidirectional prepregs were fabricated by winding Ni-plated carbon fibers (NiCF) and carbon fibers (CF). Subsequently, a series of NiCF-CF synergistically reinforced thermosetting polyimide (PI) composite materials (denoted as xNiCF-yCF/PI) were prepared with a 0°/0°/0°/0° lay-up configuration. The effects of nickel content, number of NiCF layers, and multilayer structure on the mechanical properties, electrical conductivity, and electromagnetic interference shielding effectiveness (EMI SE) of the composites were systematically investigated.Results indicate that with the increase in the number of NiCF layers, the longitudinal electrical conductivity of the composites significantly improves. The σ₁₁ value of 50%4NiCF/PI reaches 13239.53 S/m. Meanwhile, the electromagnetic shielding performance is remarkably enhanced: the EMI SET value of 50%2NiCF-2CF/PI in the X-band reaches 91.36 dB, which is a 122.81% increase compared to the non-Ni-plated composite, and its shielding mechanism is dominated by reflection. When the Ni content is 25%, the tensile strength of the 2NiCF-2CF/PI composite reaches 1035.97±33.48 MPa, with a strength retention rate of approximately 93.5%. Furthermore, the composite exhibits excellent thermal stability, with an initial decomposition temperature exceeding 450℃. This study provides a feasible design and preparation strategy for the development of high-temperature-resistant composites with both excellent electromagnetic shielding performance and good mechanical properties.