Abstract: On the basis of the decomposition of Al(OH)₃ from sodium aluminate solution, the problems of slow decomposition rate and low decomposition rate in the preparation of aluminum hydroxide from sodium aluminate solution were solved by adding the method of isopropionic alcohol dissolution. Combined with the method of ultrasonic organic pickling to remove impurity, the intergranular base in the formation of Al(OH)₃ was removed. The effects of different conditions on the decomposition results were investigated. The results show that the decomposition rate reaches 72.98% under the following conditions: a decomposition temperature of 30 ℃, decomposition time 12 h, volume ratio of isopropanol to sodium aluminate solution 1∶1. When the mass ratio of citric acid to Al(OH)₃ is 1∶2 and the concentration of acetic acid is 9 mol/L, the intergranular base in Al(OH)₃ can be effectively removed in the purification of organic acids by ultrasonic. It is found that high purity aluminum hydroxide with decomposition rate of 75.98%, D₅₀=2.539 μm and purity of 99.9034% can be prepared by means of isopropanol solution and ultrasonic organic pickling to remove intergranular alkali.