Abstract: In order to investigate the influence of the strain gradient of the reinforcement with the change of load, the theoretical analysis method was used to study the strain distribution on the reinforced concrete section, and the formula of the strain difference of the reinforcement was derived. For the reinforced concrete beam, a finite element analysis and model tests were carried out in this study. Theoretical analysis shows that the strain difference between the upper and lower edges of the reinforcement is related to the section curvature and the diameter of the reinforcement, and the section curvature is related to the load. The analysis of the test data demonstrates that during the loading process, the strain difference between the upper and lower edges of the steel bar increases with the increase of the load. The relationship between the strain difference of the compressed steel bar and the load is clearer. The strain difference ratio can be as high as 50%. The research results show that when measuring the strain of steel bars in concrete structures, the influence of the strain gradient inside the steel bars needs to be fully considered.