The invention discloses a cleaning method of a silicon wafer. The cleaning method comprises the steps of pre-cleaning, texturization, post-cleaning, pickling, cleaning and drying. According to the cleaning method, mixed liquid of hydrogen peroxide, ammonia water and deionized water is added prior to the pickling, so that metal ions of the silicon wafer can be effectively removed, organic components and particle matters on the surface of the silicon wafer can be cleaned, and smudginess of the surface of the silicon wafer can be reduced. According to the cleaning method, particles on the surfaceof the silicon wafer are removed by alkaline oxidization, and organic matters and metal pollution on the surface can be oxidized and removed, so that the silicon wafer can be cleaned cleanly, and 0.03-0.05% conversion efficiency of a battery piece can be improved.