A method for purifying a crude acetone raw material containing low molecular weight impurities using two columns is disclosed. Crude acetone raw material is fed into a first column; adding an alkaline reagent and an oxidative agent into the first column to form high molecular weight impurities; removing a top fraction from the first column by distillation to form bottom fraction containing an acetone mixture containing high molecular weight impurities; feeding the bottom fraction containing the acetone mixture obtained to a second rectification column at a charge point on the column; adding an alkaline reagent to the second column above the charge point of the bottom fraction fed; and separating a purified acetone from the high molecular weight impurities and removing the purified acetone as a top fraction by distillation in the second column, wherein the second rectification column is operated at atmospheric pressure.