The effects of macromolecular dispersant and subzero treatment on the preparation of ultrafine non agglomerative zirconia powders have been studied. The results show that adding a macromolecular dispersant at the beginning of deposition, and the subzero treatment after the wet gel being neutrality not only shorten the cleaning period, but also avoid the agglomeration of zirconia powders(particle size of 10 nm~30 nm). The mechanism is also discussed and analyzed.