Abstract: In this paper,improving the S-band performance of the microwave absorbing material is reported by utilizing frequency selective surface(FSS) with periodic metallic unit cell.Theoretical analysis of the electromagnetic wave reflection is carried out for a double layer structure consisting of FSS and microwave absorbing material using equivalent circuit of FSS and transmission line theory.The FSS structure has been designed and simulated using full-wave electromagnetic analysis based on finite element method.The FSS and microwave absorbing material double layer structure has been fabricated and its electromagnetic wave reflection has been measured.Both the experimental result and the theoretical analysis show that the performance of the double layer structure at S-band has been significantly improved,and the microwave absorbing bandwidth has been increased.