NOVELTY - Preparing isocyanatoethyl methacrylate comprises (i) taking methacrylic acid as raw material, adding a polymerization inhibitor and a catalyst, dropping mixed solution of bis(trichloromethyl)carbonate A and organic solvent A, reacting, adding ethanolamine hydrochloride and reacting to obtain aminoethyl methacrylate hydrochloride solution; and (ii) adding organic alkali, dropping mixed solution of bis(trichloromethyl)carbonate B and organic solvent B, reacting, processing the organic layer of the reaction liquid and drying.    USE - The method is useful for preparing isocyanatoethyl methacrylate (claimed).    ADVANTAGE - The method: avoids the use of toxic and harmful phosgene and production of byproducts; ensures safe production, utilizes raw materials, which are economical and easy to obtain; and ensures mild reaction conditions, produces high yield and is environmentally friendly.    DETAILED DESCRIPTION - Preparing isocyanatoethyl methacrylate comprises (i) taking methacrylic acid as raw material, adding a polymerization inhibitor and a catalyst, dropping mixed solution of bis(trichloromethyl)carbonate A and organic solvent A at 30-120 degrees C under the protection of nitrogen atmosphere, reacting for 1-10 hours, cooling to room temperature, adding ethanolamine hydrochloride at 30-120 degrees C under the protection of nitrogen atmosphere, stirring and reacting for 2-10 hours at 30-120 degrees C to obtain aminoethyl methacrylate hydrochloride solution, where the polymerization inhibitor is hydroquinone, cuprous chloride, phenothiazine, p-hydroxyanisole and/or 2,6-di-tert-butyl-4-methylphenol, the catalyst is N,N-dimethylformamide, the molar ratio of methacrylic acid, polymerization inhibitor, catalyst, bis(trichloromethyl)carbonate A and ethanolamine hydrochloride is 1:0.001-0.1:0.001-0.01:0.3-1:0.8-1.2, and the amount of organic solvent A is 2-20 times the mass of bis(trichloromethyl)carbonate A; and (ii) adding organic alkali to aminoethyl methacrylate hydrochloride solution under the protection of nitrogen atmosphere, dropping mixed solution of bis(trichloromethyl)carbonate B and organic solvent B at 40-150 degrees C under the protection of nitrogen atmosphere, reacting for 3-10 hours, processing the organic layer of the reaction liquid and drying, the molar ratio of the organic alkali and methacrylic acid is 0.1-3:1, the molar ratio of bis(trichloromethyl)carbonate B and methacrylic acid is 0.3-1:1, and the amount of organic solvent B is 1-20 times the mass of bis(trichloromethyl)carbonate B.