Abstract: Porous carbon (PC) is a promising electromagnetic (EM) wave absorbing material thanks to its light weight, large specific surface area as well as good dissipating capacity. To further improve its microwave absorbing performance, silver coated porous carbon (Ag@PC) is synthesized by one-step hydro-thermal synthesis process making use of fir as a biomass formwork. Phase compositions, morphological structure, and microwave absorption capability of the Ag@PC has been explored. Research results show that the metallic Ag was successfully reduced and the particles are evenly distributed inward the pores of the carbon formwork, which accelerates graphitization process of the amorphous carbon. The Ag@PC composite without adding polyvinyl pyrrolidone (PVP) exhibits higher dielectric constant and better EM wave dissipating capability. This is because the larger particles of Ag give rise to higher electric conductivity. After combing with frequency selective surface (FSS), the EM wave absorbing performance is further improved and the frequency region below −10 dB is located in 8.20–11.75 GHz, and the minimal reflection loss value is −22.5 dB. This work indicates that incorporating metallic Ag particles and FSS provides a valid way to strengthen EM wave absorbing capacity of PC material.