A novel single-source-precursor for SiC-TaC-C nanocomposites was successfully synthesized by the chemical reaction between a polycarbosilane (allylhydridopolycarbosilane,AHPCS) and tantalum(V) chloride (TaCl5),which was confirmed by Fourier transform infrared spectra (FTIR) measurement.After pyrolysis of the resultant single-source-precursors at 900 ℃,amorphous ceramic powders were obtained.The 900 ℃ ceramics were annealed at different temperatures in the range of 1200-1600 ℃ to gain SiC-TaC-C nanocomposites.The phase evolution of ceramic nanocomposites was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM).The results indicate that the TaC starts to crystallize at lower temperature than the β-SiC.It is particularly worth pointing out that the unique core-shell structured TaC@C nanoparticles were in-situ formed and homogeneously distributed in the ceramic matrix after annealing at 1400 ℃.Even at a high temperature of 1600 ℃,the grain sizes of β-SiC and TaC are smaller than 30 nm,fulfilling the definition of nanocomposites.The present study related to SiC-TaC-C nanocomposites paves a new road for enriching ultra-high temperature ceramic family suitable for structural/functional applications in harsh environment.