In this work, microwave-shielding behavior of epoxy thermosetting plastic reinforced with silanized Cu and Cu-Fe3O4 compound particles were studied in frequency bands E, F, I, and J. The principal aim of this work is to evaluate the significant advantage of surface-modified magnetic and conductive fillers over as-received fillers in microwave shielding. The conductive and magnetic properties of epoxy resin were improved by additions of Cu and Fe3O4 particles. Compound particles of Cu-Fe3O4 were produced by mechanical alloying process (ball milling). The compound particles were surface treated by 3-Aminopropyltrimethoxysilane (APTMS) for better dispersion in epoxy resin matrix. Functional groups on particle's surface after silane surface treatment were confirmed by FT-IR spectra analysis. The TEM images revealed that effective Cu-Fe3O4 particle compounding was formed at 1 h milling time. The maximum dielectric constant of 6.8 and magnetization of 675E(-6) were observed for surface-modified compound particle-reinforced epoxy composite designation RCF2. Similarly, maximum microwave attenuation of 35% (44 dB) was observed for surface-modified compound particle-reinforced composite designation RCF2 in 'J'-band frequency.