Abstract: The effects of different amounts of Tween-81 type non-ionic additive on the seeded precipitate from sodium aluminate solution, i.e., Al(OH)3, were studied including its particle strength, size and precipitate rate with the precipitate behavior discussed. The results showed that when the additive concentration in sodium aluminate solution is in the range from 25 to 150 mg/L, the additive can accelerate the crystallization of Al(OH)3 and improve its agglomeration to enable the increases particle size to come into the range from 45 to 75 μm with the number of fine particles reduced and the precipitation rate of the solution increased. The additives was proved available to shape the Al(OH)3 into spherocrystals which are beneficial improving the particle strength. As a whole, the favorable should be 85 mg/L and, as a result, the average particle size of hydrogen alumina is increased by 13 μm with the attrition index reduced by about 25%.