With the rapid development of communication technology, the radiation pollution caused by electronic products not only seriously affects the normal operation of electronic communication equipment, but also causes harm to human health. At present, most of the electromagnetic (EM) shielding composite lacks flexibility and is not light enough. Therefore, they are difficult to be widely used in automobile, flexible electronic industry and wearable products. In addition, these composite show a high reflection ratio of EM wave, which will cause serious secondary radiation pollution. In this study, a lightweight and flexible silicone rubber based multilayer foam was prepared through the combination of environmentally friendly supercritical carbon dioxide foaming and gradient structure design. The composite foam not only exhibits a shielding efficiency of more than 70 dB, but also achieves an absorption ratio of 81.7% at a thickness of 2.0 mm. This work is of great significance for the preparation of lightweight and high-performance EM shielding composite.