Carbon foams always show the poor mechanical properties. For application demand-oriented in the field of aerospace, carbon microspheres/Mg₂B₂O₅w hybrid reinforced carbon foam composites, were prepared by the process of compression molding and carbonization, using modified phenolic resin as carbon source, hollow microspheres as dispersed phase, and magnesium borate whisker (Mg₂B₂O₅w) as reinforcement, respectively, to improve their comprehensive performance. The mechanical properties, electromagnetic shielding effectiveness and oxidation resistance properties of carbon foam composites reinforced by carbon microspheres and different mass fractions of Mg₂B₂O₅w, were investigated by SEM, and universal testing machine, respectively. The results showed that Mg₂B₂O₅w played the role of crack deflection and bending bow, and increased the crack propagation path during compression, leading to Mg₂B₂O₅w and hollow carbon microspheres improving the compressive properties of carbon foam composites synergistically. When the mass fraction of Mg₂B₂O₅w is 2%, the compressive strength of the composites reached 11.8 MPa, 157% higher than that of pure carbon foam. The electromagnetic shielding effectiveness of carbon foam composites in the X-band increased significantly, with the increase of Mg₂B₂O₅w content. Mg₂B₂O₅w dispersed on the surface of the matrix and microsphere phases, that increased the pore structure inside the composite material, prolonged the propagation path of electromagnetic waves, and increased the absorption of electromagnetic waves. When the mass fraction of Mg₂B₂O₅w is 8%, the electromagnetic shielding performance reached 53.8 dB, 68% higher than that of pure carbon foam. Mg₂B₂O₅wpresented excellent antioxidant performance. They dispersed on the surface of the matrix and microsphere phase, preventing the contact of hot oxygen with the matrix and microsphere phase, and thus improving the oxidation resistance. When the mass fraction of Mg₂B₂O₅w is 5%, the mass loss rate of carbon foam composites is 24%, and the high-temperature oxidation resistance is the best, which is 12.1% higher than that of pure carbon foam.