Abstract: The easily soluble aluminum hydroxide was prepared by carbonation decomposition.The effects of decomposition temperature，gas passing velocity，volume fraction of CO2，and caustic molar ratio（amount?鄄of?鄄substance ratio of sodium oxide to alumina） of sodium aluminate solution etc.on the aluminum hydroxide′s acid solubility were investigated.Results showed that the optimum conditions：the carbonation decomposition temperature was 65～75 ℃，gas passing velocity was 400 L/h，the volume fraction of CO2 was 30%～38%，and the caustic molar ratio of sodium aluminate solution was 1.48.The acid soluble rate of the product was more than 95% under those conditions.The product was characterized by XRD and SEM，and the results showed the acid solubility mainly depended on the phase composition of aluminum hydroxide.

Key words: easing soluble aluminum hydroxide, carbonation decomposition, CO2, acid solubility, crystal structure