Core-shell ceramics fibers with multiple composition are ideal candidates for thermal insulation application at high temperature. Herein, ultrathin C-SiC/ZrSixOyCz core-shell fibers were successfully fabricated by coaxial electrospinning and high temperature pyrolysis with polycarbosilane (PCS) as core precursor and Zirconium butoxide as shell precursor, respectively. The ceramics fibers revealed distinct core-shell partition. The average diameter was about 3 μm and the shell thickness increased to 500 nm with increasing pyrolysis temperature. Thermogravimetry analysis (TGA) results showed that the weight of the fibers reduced to 60 % in Ar atmosphere and rose to 108 % in O2 atmosphere, which confirmed the excellent thermal stability and anti-oxidation properties due to the protection effect of shell layer and the self-healing mechanism. Moreover, the ceramics fibers maintained good flexibility and deformability. Such optimized anti-oxidation and mechanical performance indicates that the prepared core-shell fibers could be an excellent thermal insulation material for high temperature application.