The invention discloses a gelatinization method for modified starch. The gelatinization method comprises the following steps: 1) firstly, preparing modified starch suspension at the room temperature; 2) carrying out initial gelatinization on the modified starch suspension at the low temperature to form starch slurry; and 3) carrying out secondary gelatinization on the modified starch of the starch slurry at a high temperature, and finally, quickly cooling the modified starch subjected to the secondary gelatinization. Compared with a common one-step type heating and heat-preserving process, the method can shorten the whole gelatinization time and can weaken damages of starch particles in a gelatinization process, so that the gelatinization degree and gelatinization uniformity of the modified starch are precisely controlled, and therefore, the problem of uneven starch gelatinization in a conventional gelatinization process is solved.