The invention discloses a preparation method of spherical cristobalite, and belongs to the technical field of inorganic materials. The preparation method comprises following steps: spherical cristobalite powder and an isolating agent are mixed at a certain ratio, an obtained mixed powder is introduced into an electric furnace under inert gas protection, and is heated at certain heating conditions,an obtained powder is subjected to calcining at an aerobic environment, a powder product obtained through calcining is subjected to washing and drying so as to obtain spherical cristobalite products.The preparation method of spherical cristobalite comprises following three steps: mixing of spherical cristobalite powder and the isolating agent; conversion of spherical cristobalite powder into spherical cristobalite; removing of the isolating agent, and washing and drying of spherical cristobalite. The spherical cristobalite prepared using the preparation method is high in purity, low in surface energy, and regular in morphology, and is suitable for large scale applications as a filling material.