In order to retard the sweetness characteristics of sucralose, microencapsulation technology was used to encapsulate sucralose. Soybean isolate protein and sodium alginate were selected as wall materials and sucralose as the core material, and the composite coalescence method was used to prepare sucralose microcapsules. Microencapsulation yield was used as the evaluation index. The optimum preparation conditions were determined using one-factor test and response surface methodology, while the morphology and other characteristics were characterized.The results of the study showed that the optimal preparation process of microcapsules was as follows: the compound coagulation pH value was 3.01, the mass ratio of core to wall was 1.27, the mass ratio of soybean isolate protein and sodium alginate was 3.01, and the wall mass concentration was 0.0304 g/mL. The sucralose microcapsules prepared according to this process condition were in complete spherical shape with smooth and flat surface, and the particle size was about 50 μm, with the yield up to 75.19%.