The invention discloses a preparation method and application for micron vaterite type food-grade calcium carbonate. By adopting a gas-liquid two-phase carbonization process and an in-situ surface modification process to prepare vaterite type food-grade calcium carbonate, the preparation method concretely comprises the following steps: with limestone as a raw material, grinding the raw material into powder, carrying out dissolving by utilizing acid, then adding H2O2, H2SO4, Ca(OH)2 and the like, and removing impurities like Fe, Ba, Mg, Al, Cd and Hg so as to obtain a pure calcium solution; and adding ammonia water, a controlling agent with a food-grade crystal form and an anti-settling agent into a CaCl2 solution, introducing CO2, and carrying out gas-liquid two-phase carbonization reaction so as to prepare the micron vaterite type food-grade calcium carbonate with good dispersion and suspension performances, wherein the micron vaterite type food-grade calcium carbonate is micron spherical calcium carbonate and has a stable crystal form. The calcium carbonate product prepared by using the method provided by the invention is spherical particles, is fine and uniform, has good dispersity and suspension property and strong settlement resistance, can be directly used as a calcium strengthening agent in liquid beverages like milk, soymilk and fruit juice.