Polystyrene (PS) microspheres have the advantages of good stability, corrosion resistance and low density, which have a broad application prospect. In this paper, PS composite microspheres with 20% silver plating content were prepared by chemical plating method and incorporated into polydimethylsiloxane (PDMS) flexible matrix to prepare Ag@PS/PDMS flexible wave-absorbing materials. The electromagnetic parameters were adjusted to optimize the dielectric and wave-absorbing properties by varying the additional amount of Ag@PS composite microspheres in Ag@PS/PDMS composites. The X-ray diffraction (XRD) results proved the successful preparation of Ag@PS composite microspheres. The SEM and EDS images indicated that the Ag particles were attached to the external surface of PS. The presence of Ag particles in the Ag@PS composite microspheres enhances their electrical conductivity and enables the formation of a conductive network. This, in turn, improves the composites’ dielectric constant. The optimal wave-absorbing capability of the composites was achieved when the Ag@PS composite microspheres were added at a weight percentage of 50%. When the sample attains a thickness of 1.8mm, a reflection loss of at least ?39.8dB is attained at 10.4GHz, along with a bandwidth of 1.6GHz (9.1–10.7GHz) for the effective absorption bandwidth (EAB). The pressure-sensitive properties of the pliable composites were investigated as well. The optimal pressure-sensitive performance of Ag@PS/PDMS composites was achieved with a 60wt.% addition of Ag@PS composite microspheres. The resistance undergoes significant changes when subjected to pressure with a sensitivity of 9.7. The results indicate that the flexible composites’ wave-absorption and pressure-sensitivity properties can be modulated by adjusting the amount of Ag@PS composite microspheres added.