The invention belongs to the technical field of chemical preparations, and particularly relates to a preparation method for electronic-grade triglycidyl isocyanurate. The method specifically comprisesthe following steps: uniformly mixing cyanuric acid, epoxy chloropropane, organic strong base and water, reacting for 1.5 h at 75-80 DEG C; heat-insulating for 1 h at 100 DEG C; in vacuum, 35-40 DEGC, adding sodium hydroxide; vacuum-unloading, removing a solid phase, adding clear water to mother liquor, stewing and removing superstratum saline water; in vacuum, 60-70 DEG C, evaporating a part ofepoxy chloropropane from the substratum mother liquor; placing a distilled material in a crystallization kettle, stirring, at 8-10 DEG C, and removing a liquid phase; decompressing the solid phase, and microwave-drying, to obtain a final product. The catalyst is the organic strong base which does not contain halogen, and the final product has not a halide ion residue. A cyclization process is alkalified in vacuum, so epoxy chloropropane hydrolysis caused by alkaline water and a by-product produced by TGIC cycle opening are avoided. The technical scheme of the preparation method is used, so the product quality is apparently improved, the product cost and the energy consumption are greatly reduced, and the environment is friendly.