Abstract: Trilobal polycarbosilane(PCS) fibers were prepared by melt spinning PCS precursor through Y-shaped spinneret. Then, after curing in air and heat treatment under N₂ atmosphere, trilobal silicon carbide fibers were manufactured. The effect of spinning temperature and velocity on the fibers degree of profile was analyzed. Preparation conditions such as curing, heat-treatment and microwave-absorbing properties were also studied. Compared with circular SiC fibers, the fiber exhibits higher mechanical properties and microwave-absorbing properties. The structural radar absorbing materials, composed of the fibers with resin, exhibit a reflection attenuation amount of 10~20 dB in the range of 8~18 GHz.