To study the effect of different cross-section types on properties of carbon fibers, the microstructures of triangleshape
carbon fibers and circle-shape carbon fibers were investigated by scanning electron microscope, X-Ray
Photoelectron Spectroscopy and X-ray diffraction. The mechanical properties and electromagnetic properties of
carbon fibers reinforced plastics were also studied. Results show that their microstructures and tensile-strength were
similar, while the imaginary part of complex dielectric constant and loss tangent of the triangle-shape carbon fiber
reinforced plastics are higher than those of the circle-shape carbon fiber reinforced plastics. The triangle-shape
carbon fiber reinforced plastics have both the function of load bearing and the electromagnetic energy absorbing
capability, and the composites will become promising radar absorbing structure material.