The invention discloses a preparation method of a functional ceramic body. The preparation method is prepared from the steps of: a, sieving ceramic body particles; b, mixing a functional material powder, a solvent and a modified additive to obtain functional slurry; c, coating the ceramic body particles with the functional slurry; d, aging; and e, carrying out compression moulding and sintering to form the functional ceramic body. With the adoption of the preparation method, the problem that the forming performance of the ceramic body becomes poor due to the addition of the functional material powder can be solved. The preparation method in which the ordinary ceramic body particles are coated with the liquid functional slurry can ensure the forming performance of the ceramic body which is prepared by adopting a secondary mixing process, can further reduce the dosage of the functional material powder, can lower the cost and has outstanding technical advantages.