Provided are a SiC/ZrC composite fiber, a preparation method and use thereof. The SiC/ZrC composite fiber has a diameter of 10 to 70 μm. The method includes mixing liquid polycarbosilane with a zirconium-containing polymer to obtain a hybrid spinning solution, and then performing electrospinning to obtain a SiC/ZrC composite fiber precursor, crosslinking and thermally treating the SiC/ZrC composite fiber precursor in a protective atmosphere to obtain the SiC/ZrC composite fiber. The SiC/ZrC composite fiber is continuous and uniform, has an adjustable diameter, and thus has outstanding tensile strength and breaking strength and excellent high-temperature resistance. Without use of any organic solvent or spinning agent, the method achieves short process flow and high yield, indicating wide application prospects.