Prestressed concrete structures are subject to environmental corrosion during service, resulting in corrosion of the reinforcement and varying degrees of damage to the structure. This leads to a reduction in the structural load carrying capacity. To investigate the effect of the reinforcement corrosion on the flexural performance of prestressed concrete beams, corroded prestressed concrete beams were tested by a four-point bending test. It is shown that the corrosion of the ordinary reinforcement has a small effect on the cracking strength and ultimate strength of test beams. However, the effect of corrosion on the yield load is more obvious. When the corrosion rate of ordinary steel reinforcement is 3.8%, the yield load of the test beams decreases by 15.6%. Additionally, the corrosion rate of steel reinforcement has a smaller effect on the yield deflection of the test beams, but the effect on the ultimate deflection is more obvious. When the corrosion rate of steel reinforcement is 11.5%, the ultimate deflection decreases by 8.6%. The corrosion of the prestressed steel strand has a significant effect on the cracking load and yield load of the test beams, which is the main factor affecting the load carrying capacity and deformation capacity of the prestressed beams. The cracking load of the test specimen decreases by 32.9% when the strand corrosion rate is 7.6%.Based on experimental data, finite element software ABAQUS is used to simulate the finite element calculation of each corroded beam. Meanwhile, a calculation method for the bearing capacity of prestressed concrete beams with corroded ordinary steel bars and corroded steel strands was proposed, based on the performance degradation patterns of corroded reinforcement. Both calculated and simulated results show good agreement with experimental data.