The carbon fiber composite materials have garnered significant interest in structural reinforcement applications. It is worth further studying how much the use of this material in embedded end-anchored reinforcement of concrete box girders affects its load-bearing capacity. Two finite element analysis models considering the slip and binding contact between carbon fiber mesh and polymer mortar were established using the finite element software Abauqs. A concrete box girder model was designed and tested. The research results showed that the finite element analysis results were in good agreement with the experimental results. The finite element analysis model without considering the slip of the reinforcement layer interface under normal service limit conditions was closer to the experimental results, while the finite element analysis model considering the slip under the ultimate bearing capacity limit conditions was more consistent with the experimental results. The influences of the bonding position, bonding width, bottom grid layer number, and U-shaped hoop crossing angle of the grid U-shaped hoop on the bending capacity of the reinforced concrete box girder were analyzed. The analysis results show that the anchoring position and anchoring width had a certain impact on the deflection and failure mode of the component, and the anchoring amount and bottom grid layer number should be proportional. However, the change in the crossing angle of the anchoring strip had little effect on the bending performance of the girder. The analytical methods and findings presented in this study offer valuable insights for engineers and engineering projects.