Abstract: Starch retrogradation is a major cause of quality deterioration and shortened shelf life in starch-based foods during storage. This study investigated the effects and mechanisms of soluble soybean polysaccharides (SSPS) with different molecular weights on the retrogradation behavior of potato starch during storage. The changes of gel hardness, water distribution, retrogradation degree, retrogradation kinetics, crystalline structure, and short-range ordered structure during storage were analyzed to understand the impact of different molecular weight SSPS on starch retrogradation. The addition of three SSPS with different molecular weights significantly reduces the hardness, crystallinity, short-range order, and retrogradation degree of starch gels, and decreases the water migration (P<0.05). The results showed that all three SSPS could inhibit the retrogradation of starch gels during storage. Notably, L-SSPS had the strongest ability to inhibit starch retrogradation. L-SSPS inhibited the retrogradation of potato starch gels mainly because L-SSPS had a small molecular weight and short molecular chains, and contained more hydroxyl groups. This allowed it to compete more effectively with starch for water molecules, thereby inhibiting the recrystallization of amylose and amylopectin and retarding the retrogradation process of starch gels. Avrami kinetic analysis revealed that the addition of SSPS reduced the crystallization rate constant k of the starch gel and prolonged the half-retrogradation time t_1/2. It provides a scientific basis for the SSPS molecular weight on starch retrogradation behavior, providing theoretical guidance for improving the quality of starch-based foods and extending their shelf life.