Abstract: Against the backdrop of the Belt and Road Initiative, engineering development and construction in tropical island areas along its routes have been accelerated, requiring a large amount of building materials. However, local traditional building material resources are lacking, while local coral, seawater, and other resources are abundant. Therefore, in the construction of island and reef projects, such as port terminals and roads, it is of great importance to prepare coral aggregate concrete beams (CACBs) on–site using coral, coral sand, and seawater. However, in the tropical marine environment with high wind, humidity, temperature, and radiation, the reinforcing bars inside CACBs are highly prone to rust, threatening the safety of structures. The shear failure of reinforced concrete beams is a typical brittle failure, and its failure risk is much greater than that of the same type of bending failure. Recently, numerical simulation technology has been widely used in the engineering field. Compared with traditional testing methods, it has the advantages of repeatability, strong controllability, low cost, and high time efficiency. Therefore, conducting research on the shear performance of different types of reinforcing bar CACBs by combining experiments and numerical analyses is of great scientific and engineering importance for the engineering construction and restoration of tropical islands and reefs. This study conducts experimental research on the shear performance of CACBs with different types of reinforcing bars through a combination of experiments and numerical simulations. Based on the experimental results, the constitutive model parameters of CACBs were determined, and a numerical analysis model of the shear performance of CACBs based on the Karagozian & Case (K&C) theory was established to analyze its crack development, failure deformation, and shear bearing capacity. Relationships such as the load–deflection curve and load–reinforcement strain were established, and the influence laws of different factors on the shear performance of CACBs were clarified. The results show that the type of steel bar has a significant influence on the shear performance of CACBs because ordinary steel bars rust easily, while stainless and coated steel bars can effectively inhibit corrosion. When the shear failure of CACBs occurred, the strain of ordinary steel bars was higher than that of newly coated organic steel bars. In addition, based on the K&C theory, a numerical analysis model for describing the shear resistance of CACBs was proposed. The applicability of the numerical model in CACBs ranging from C30 to C60 was verified. This model could better describe the oblique section failure morphology throughout the entire CACB process. The errors between the simulated and measured values of V_cr and V_cs, respectively, and the midspan deflection were all less than 18%. The shear bearing capacity calculated using the proposed numerical model improved by 63% and 31% compared with JGJ/T 12-2019 and GB50010-2010, respectively, and by 4% compared with the calculation formula proposed by the research group in the early stage. This indicates that the numerical model can effectively characterize the variation law of the shear performance of CACBs.