The changing rule and removal mechanism of carbonate from sodium aluminate solution with lime addition, digestion temperature, seed addition and carbonate concentration were systematically investigated by XRD, XRF, SEM-EDS and PSD methods. The results show that when the mass concentration of carbonate in sodium aluminate solution is 25 g · L -l, the optimum digestion conditions of alumina and removal conditions of carbonate were lime addition of 11 % and reaction temperature of 270 ℃, and the corresponding digestion rate of alumina and removal rate of carbonate were 72. 47% and 68. 95% respectively. Cancrinite ( Na6 ( Al6Si6 0 24 )· Na2C03 • 2H2 0) with panel structure is the main product in the carbonate removing process. Carbonate is easier to be removed from sodium aluminate solution when its concentration is lower than 25 g · L - l . <摘要译文>