SiC nanowires (SiCnws) with different morphologies have great potential for the reinforcement of ceramic materials. But it is a big challenge in the in-situ synthesis of SiCnws in the ceramic powders which is critical to ensure high reinforcing effects. For the reinforcement of ZrB2-ZrC composites, a simple method is developed to in-situ fabricate SiCnws with various morphologies in nano-sized ZrB2-ZrC powders through pyrolyzing ZrB2-ZrC-SiC gel precursors. The prepared ZrB2-ZrC ceramic powders have mean diameter of about 100 nm with uniformly distributed SiCnw in morphologies of nanocylider, bead-like, bamboo-shape with tunable nodes, chain-like and hexagonal prisms were prepared by optimizing the preparation process. Moreover, the SiCnws were in a diameter of ranging from 100 to 400 nm, while the length was controlled from tens to hundreds of microns. The generation of ZrB2/ZrC can determine the formation of SiCnws with specific morphologies by producing CO gas to affect the local supersaturation of the SiO and CO vapors. The study provides an opportunity for fabricating SiCnw reinforced ceramic materials with enhanced strengthening effect and also overcome its critical fabrication process.