A method for purifying an aqueous potassium hydroxide solution having rich silicon impurities has been disclosed in the invention, which is particularly related to a method that utilizes a low-carbon alcohol (such as ethanol) for extracting said aqueous potassium hydroxide solution, and includes the steps of mixing a low-carbon alcohol with an aqueous potassium hydroxide solution having rich silicon impurities; allowing the resulting mixture therefrom to divide into an aqueous phase layer and a low-carbon alcohol phase layer that contains the aqueous potassium hydroxide solution with reduced silicon impurities, and subjecting the low-carbon alcohol phase layer to a separation process for removing the low-carbon alcohol, thereby resulting in an aqueous potassium hydroxide solution having reduced silicon impurities.