The electromagnetic and microwave absorbing properties of FeCoB powder composites prepared by single-roller melt-spinning and mechanical milling processes were investigated in this paper.The result indicates that the flake-like powders are obtained.As milling time increases,the flake-like powder particles tend to agglomerate,causing the flake-like powders decrease gradually.The milling time plays an important role in the electromagnetic parameters which relates to the shape and size of the powder particles.The calculation shows that the sample milled for 6 h could achieve an optimal reflection loss of-11.5 dB at 5.8 GHz,with mass fraction of 83%and a matching thickness of1.8 mm.The result also indicates that the microwave absorbing properties of the FeCoB powder composites are adjustable by changing their thickness,and can be applied as a thinner microwave absorbing material in the range of2–8 GHz. The electromagnetic and microwave absorbing properties of FeCoB powder composites prepared by single-roller melt-spinning and mechanical milling processes were investigated in this paper. The result indicates that the flake-like powders are obtained. As milling time increases, the flake-like powder particles tend to agglomerate, causing the flake-like powders decrease gradually. The milling time plays an important role in the shape of the powder and the particles of the powder particles. The calculation shows that the sample milled for 6 h could achieve an optimal reflection loss of-11.5 dB at 5.8 GHz with mass fraction of 83% and a matching thickness of 1.8 mm.The result also indicates that the microwave absorbing properties of the FeCoB powder composites are adjustable by changing their thickness, and can be applied as a thinner microwave absorbing material in the range of 2-8 GHz.