The invention discloses a treatment method for recycling waste silicon sludge. The method comprises the steps as follows: (1) sequentially placing waste silicon sludge in a first reaction tank, a second reaction tank, a third reaction tank, a fourth reaction tank and a fifth reaction tank for cleaning, magnetic separation, cleaning, acid pickling and cleaning; (2) mixing the waste silicon sludge obtained from the step (1) with deionized water in a solid-liquid ratio being 1:(5-50) to form slurry, and adding a dispersant for dispersion; (3) spraying the slurry obtained from the step (2) into areaction chamber under high pressure, wherein the slurry is subjected to an oxidation reaction in the reaction chamber to form silicon dioxide particles; (4) collecting the particles obtained from step (3) by a cyclone dust collector to obtain high-purity micro silicon dioxide powder particles; (5) performing size grading on the powder particles obtained from step (4) to obtain high-purity silicondioxide powder with uniform particle size larger than 99%. Therefore, the high-purity silicon dioxide powder can be widely applied to industrial filling materials and the waste silicon sludge can berecycled.