Abstract: This study analyzes the shear damage behavior of CFRP-reinforced concrete beams of different sizes without web reinforcement. The analysis is based on shear damage test results of six specimens. The CFRP sheets were applied at the adhesive angles of 45° and 90°. The analysis was conducted using an extension of the ABAQUS finite element software. The shear damage behavior of the RC beams was examined through the adhesive angles of 0°, 30°, 45°, 60°, and 90°. The specimens of identical dimensions alone varied in the angle of adhesion between CFRP sheet, while all other parameters remained constant, meaning that the qualities of the RC beams remained unchanged. The study examined how the adhesion angle of CFRP sheet affects the shear performance and size-effect behavior of RC beams reinforced with CFRP sheets. The findings indicate that the angle at which the CFRP sheet is attached has minimal impact on the damage mode of RC beams. Additionally, the strain distribution on the CFRP sheet is responsive to crack extension. The strain value increases as the CFRP sheet gets closer to being perpendicular to the main diagonal crack, resulting in a stronger reinforcing effect. Consequently, the shear capacity and stiffness of the beams also increase, while the dimension effect on shear strength weakens. Based on the experimental and simulation results, a law is provided for the dimensional effect of shear strength in CFRP-reinforced RC beams without web reinforcement, taking into account the angle of CFRP sheet adhesion.