Some concrete structures are subjected to low-velocity but repeated impacts during their service life. Considering the favorable performance of cementitious composites containing expanded polystyrene beads, as well as the sandwich structure's ability to withstand impact loads, and given the lack of research on how structural parameters affect performance, this study examined the influence of these parameters on the impact resistance of sandwich structures under repeated low-velocity impacts. The impact tests were conducted using a drop-weight method. The cementitious composite containing expanded polystyrene beads was used as the core material of the sandwich structure. The results showed that the relative core thickness, the relative position of the core, and the core density all significantly affect the impact strength of the structure. Among these factors, the impact strength of the sandwich structure was most sensitive to the relative position of the core and least sensitive to the core density. Therefore, to achieve maximum resistance against repeated low-velocity impacts, the following solutions are recommended. In the first priority, the relative thickness of the skin which is exposed to the impacts should be increased. Secondly, the relative thickness of the core should be reduced. In the third priority, the density of the core should be increased. In addition, as a suggestion for future studies, enhancing the bonding of expanded polystyrene beads to the mortar by additives such as silica fume and metakaolin can be a helpful solution.