The invention relates to a method for preparing a rare earth-doped ferrite/polythiophene/carbon nano tube microwave absorbent. Barium nitrate, ferric nitrate, neodymium nitrate, lanthanum nitrate, thiophene monomers and carbon nano tubes serve as main raw materials. Rare earth-doped ferrite is prepared by adopting a sol-gel auto-combustion method, and then a rare earth-doped ferrite/polythiophene/carbon nano tube composite is prepared by adopting in-situ chemical oxidation. The microwave absorbent is mainly used for solving the problems of narrow band, high density, weak absorption and high thickness of a single ferrite wave absorption material, and is ideal.