The invention discloses a method for post-cleaning a silicon wafer by utilizing CMP equipment. The method comprises the following steps: introducing cleaning liquid into the CMP equipment, after a chemical mechanical polishing machine finishes polishing work of a conventional silicon wafer polishing process, replacing a polishing disc, opening a cleaning liquid pipeline, closing a polishing liquidpipeline, and entering into a cleaning process; after the cleaning process is finished, closing the cleaning liquid pipeline, opening a deionized water pipeline, introducing deionized water, and performing deionized cleaning; and finally taking out the silicon wafer, and blowing nitrogen to dry 15-30s, and finishing the polishing and cleaning processes. The cleaning method has simple process andno secondary pollution, achieves integration of polishing and cleaning, reduces investment of special cleaning equipment and improves cleaning efficiency.