The use of coral aggregate concrete (CAC) as a novel construction material has attracted significant attention for the construction of reef engineering structures. To investigate the static splitting-tensile behaviors of CAC under the influence of two factors, namely specimen geometry and bearing strip size, a three-dimensional (3D) mesoscale modeling approach with consideration for aggregate randomness in shape and distribution was adopted in this study. We established 12 different specimen models with two specimen shapes (i.e., a cube with an edge length of 150 mm and a cylinder with dimensions of ϕ150 mm × 300 mm) and six strip widths (i.e., 6, 9, 12, 15, 18, and 20 mm) for calculation. The effects of specimen geometry and strip width on the splitting-tensile properties of CAC, such as failure processes, final failure patterns, and splitting-tensile strength (fst), are analyzed and discussed systematically. The results indicate the high reliability of the developed mesoscale modeling approach and reveal the optimal computational parameters for simulating and predicting the splitting-tensile properties of CAC. The fst values of CAC are associated with both the specimen geometry and width of the bearing strip. The fst values of the cube model are slightly higher than those of the cylinder model for the same bearing strip size, representing geometry effects that can be explained by differences in fracture area. Additionally, the fst value of CAC gradually increases with the relative width of the bearing strip ranging from 0.04 to 0.13. Based on the elastic solution theory, the variation area of CAC fst values with the relative width of the bearing strip was determined preliminarily, which has great significance for studying the tensile performance of CAC.