A method for polishing Through-Silicon Via (TSV) wafers is provided. The method comprises a step of subjecting the surface of a TSV wafer to a polishing treatment with a polishing composition containing an organic alkaline compound, an oxidizing agent selected from sodium chlorite and/or potassium bromate, silicon oxide abrasive particles, and a solvent to simultaneously remove Si and conductive materials at their respective removal rates. By using the method of this invention, Si and conductive materials can be simultaneously polished at higher removal rates to significantly save the necessary working-hour costs for polishing TSV wafers. A polishing composition used in the above method is also provided.