The invention relates to a preparation method for high-purity quartz sand, and concretely relates to a purification technology for high-purity quartz sand applicable to prepare a monocrystalline silicon arc quartz crucible. The preparation method comprises: employing quartz as a basic raw material, performing crude washing, crushing, roasting, water quenching, crushing grading, electric-field induction diffusion, hot-pressing acid washing, hot-pressing alkali washing, electric-field intervention flotation, chlorination processing, sand baking, magnetic separation and the like, so as to obtain the high-purity quartz sand with the impurity total quantity controlled in 16 ppm and the purity larger than 99.99%. In the method, the electric-field induction diffusion technology is employed to induce impurity ions in quartz to be diffused to the surfaces of quartz sand particles, then the hot-press acid washing and hot-pressing alkali washing technology is employed for substantially improving the leaching efficiency of impurities in quartz sand, and the electric-field intervention flotation technology helps to improve the floatation removal efficiency of impurity particles.