The invention discloses a silicon dioxide pellet and a preparation method thereof. A micro pellet core with the grain size of 0.1 to 3.5mm is prepared from a main material which at least consists of silicon dioxide or microcrystalline cellulose, and a binding agent, wherein the main material accounts for 60 to 95 percent; the binding agent accounts for 3 to 25 percent; and water accounts for 2 to15 percent. The preparation method comprises the following steps of: mixing the main material and the binding agent, preparing approximately round grains in a granulator, and drying and sieving the grains to obtain the silicon dioxide, wherein the main material is formed by mixing silicon dioxide fine powder and the microcrystalline cellulose. The invention is characterized in that: the manufacturing process is simple, the raw material sources are rich, the silicon dioxide pellet is convenient and reliable to use, the quality of the micro silicon dioxide pellet completely meets requirements, the demands of domestic and foreign manufacturers can be met, needed samples can be provided for scientific research academies and research and development departments for preparation innovation in time, the localization of sustained-release preparations is promoted, and the like.