Abstract: A new limestone treatment process was developed for the waste alkaline etchant,containing alkaline etching reagent,from mat-forming treatment of aluminum.The simple and efficient process has the highest Al reduction rate of 97% and NaOH recovery rate of 80% and can realize commercial production. Additionally it requires cheap raw materials and the by-products(CaCl22H2O,Al2(SO4)318H2O and CaSO4) also have high utilization values.