Abstract: The metal-coated PMI foam materials were prepared by magnetron sputtering using different metal targets as raw materials and PMI foams as substrates. The electrical properties were optimized and multilayer PMI foam microwave absorbing materials were prepared by pressure molding. It is found that the coating materials played an important role in the microwave absorbing property. Four kinds of coating materials were tested: Al, Ti, Ni and Co, and their reflectivity gradually increased. The control of coating time also had a great influence. The reflectivity of Ti-coated PMI foams increased firstly and then decreased with the coating time increasing. The reflectivity of Ni-coated PMI foams and Co-coated PMI foams gradually deteriorated with the increase of coating time. The Co-coated PMI foams with different coating times were used for the optimization of multilayer microwave absorbing materials, and 6 kinds of optimized schemes were obtained. The 6# multilayer Co-coated PMI foam material had the best microwave absorption properties. Finally, Multilayer PMI foam microwave absorbing materials were prepared by pressure molding. The reflectivity curve of the multilayer PMI foam microwave absorbing material had a red shift comparing with the calculation result, but the overall trend matched well with the calculation result.