According to the preparation method of the microcapsule-coated phytate epoxy resin flame retardant, renewable resource phytate is used as a raw material, phytate is taken or prepared according to needs, microcapsules are adopted for coating the phytate, the dispersity of the phytate in epoxy resin is improved, and the flame retardant effect is improved, wherein microcapsule coating raw materials comprise epoxy resin (E51), 2-methyl-4-ethylimidazole, ethanol and sodium dodecyl benzene sulfonate. The preparation method comprises the following steps: reacting sodium phytate with magnesium chloride for a period of time under certain conditions, and washing, filtering and drying a product to obtain a product A; mixing the epoxy resin with the ethanol, adding the product A and the sodium dodecylbenzene sulfonate, fully stirring for a period of time, adding the 2-methyl-4-ethylimidazole, reacting under a certain condition, and carrying out suction filtration, washing and drying on the product to obtain a product B; the product B can be fully dispersed in the epoxy resin, the influence on the mechanical property of the cured epoxy resin is small, and the flame retardant property of the epoxy resin can be effectively improved.