Abstract: In order to reasonably evaluate the residual bending capacity of existing corroded reinforced concrete beams and establish a reasonable and scientific calculation model for the flexural capacity of corroded reinforced concrete beams, considering the degradation of mechanical properties and section damage of sulfuric acid corrosion concrete, the degradation of mechanical properties of corrosion reinforcement and the influence of reinforcement strength utilization coefficient, a calculation method of flexural bearing capacity of reinforced concrete beams after sulfuric acid corrosion was proposed. Calcalated results were in good agreement with experimental ones. The results showed that with the decrease of pH value, the influence of sulfuric acid corrosion on the flexural capacity of beams increased; the higher the strength grade of concrete, the faster the bearing capacity of beams decreased; when the reinforcement was not corroded, the bearing capacity of beams decreased with the increase of the thickness of concrete corrosion layer.