Abstract:High-entropy alloys have great potential advantages and broad applications in the field of wave absorption due to their applicability in harsh environments and various attenuation mechanisms for electromagnetic fields. The element Cu is widely used because of its excellent ductility and electrical conductivity. In this paper, Cu elements were added to investigate the wave absorption properties of Al1.5Co4Fe2CrCux (x = 0.5, 1.0, 1.5, 2.0; mole ratio) high-entropy alloys with different Cu contents. Al1.5Co4Fe2CrCux high-entropy alloys prepared by mechanical alloying were flaky, granular, and ellipsoidal in shape and had soft magnetic properties. The saturation magnetization strength gradually decreased with increasing Cu content, while the coercivity gradually increased. Besides, the addition of Cu elements helped to form powder particles with large aspect ratios, modulate the magnetic and electromagnetic properties of alloy powders, and further enhance the dielectric loss capability of alloy powders. Al1.5Co4Fe2CrCux high-entropy alloy powders with x =1.0 had the highest attenuation coefficient at different Cu contents, and their minimum reflection loss was -16.50 dB at a thinner thickness of 1.50 mm. Their effective absorption bandwidth in the Ku band reached 4.80 GHz at a thinner thickness of 1.70 mm, showing good absorption performance.