In order to study the reinforcement effect of common reinforcement methods on full-scale models of prestressed concrete T-beams, relied on beam replacement engineering, and taking the replaced diseased T-beams as experimental research objects, common reinforcement methods including prestressed carbon fiber board reinforcement, steel plate bonding reinforcement, joint sealing reinforcement, and external prestressed steel tendon reinforcement were used to verify the reinforcement effect. The deflection, steel strain, and crack development were analyzed. The experimental results show that compared to unreinforced beams, the external prestressed steel strands have the most prominent reinforcement effect, with a 136% increase in cracking load, an 84% increase in yield load, and a 37% increase in ultimate load, and the original cracks are basically closed. This indicates that prestressed carbon plate reinforcement, bonded steel plate reinforcement, and external prestressed steel tendon reinforcement have good effects on improving the stiffness of the beam, delaying the development of original cracks, suppressing the generation of new cracks, and improving the bearing capacity. However, external prestressed steel tendon reinforcement has the most significant improvement effect in all aspects.