Using cotton as carbon source and template, SiC microtubes were prepared by the carbothermal reduction of a cotton-contained precursor, which was obtained by impregnating cotton in tetraethyl orthosilicate solution. To characterize the product, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and network analyzer were used. The results show that the SiC microtubes with surfaces composed of villus-like beta-SiC nanowires have a length of tens to hundreds of micrometers and a diameter of several to 20 mu m. SiC microtubes achieve a reflection loss below -10 dB (90% absorption) at different frequencies, and the minimum value is -23.9 dB at 17.5 GHz when its thickness is 1 mm.