Abstract: Provided are a high-entropy carbide ceramic, a rare earth-containing high-entropy carbide ceramic, fibers thereof, precursors thereof, and preparation methods thereof. The precursor includes at least four elements selected from Ti, Zr, Hf, V, Nb, Ta, Mo, and W, with each metal element accounting for 5-35% of the total molar quantity of metal elements in the precursor. The rare earth-containing high-entropy carbide ceramic precursor includes at least four transition metal elements and at least one rare-earth metal element. The high-entropy ceramic is a single-crystal-phase high-performance ceramic prepared from the precursor, with each element being homogenously distributed at molecular level.