Abstract: A new technology of preparing nano-sized alumina by recovering aluminium in aluminium ash was introduced.Aluminium sulfate solution could be got by using sulfuric acid to leach aluminium ash produced in electrolytic aluminum industry.Influence of every factor on leaching process was investigated and optimum conditions were obtained.Precipitate of ammonium aluminum carbonate hydroxide（AACH） was produced in the reaction of aluminium sulfate and ammonium bicarbonate.Alumina was finally received by filtration,lavation,and calcination from AACH precipitate.Influences of factors,such as style and quantity of dispersing agent and concentration of ammonium sulfate on particle size of alumina,were investigated and optimum conditions were obtained.XRD and SEM results showed that the product was α-Al<SUB>2</SUB>O<SUB>3</SUB> with particle size of about 70 nm. 