The invention discloses a preparation method for isocyanate-modified epoxy acrylate, which comprises the following steps that: the epoxy resin and the inhibitor are added in a reaction vessel and themixtures are stirred at a speed ranging from 150 to 250r/min so as to raise the temperature to 90 to 100 DEG C; then the mixtures of the acylic acid and the catalysts are added in drop by drop and theobtained mixtures are stirred to carry out a reaction for 3 to 4 hours at a speed ranging from 250 to 350r/min with controlling the temperature to rang 110 to120 DEG C so as to obtain the epoxy acrylate; the temperature of the mixtures in the reactor vessel is lowered to 50 to 60 DEG C and then the isocyanate is added in the mixtures drop by drop, and the mixtures are stirred to conduct the reaction for 0.5 to 2 hours at a speed ranging from 250 to 350r/min so as to obtain the modified epoxy acrylate. The light-cured resin obtained through the method of the invention has lower viscosity and excellent flexibility.