Abstract: This paper investigates the structure internal force redistribution, the sectional strain and stress redistribution and long-term flexural deformation of reinforced concrete continuous box girders. To do that, 1006 days’ long-term behavior test is carried out, and concrete shrinkage, creep and uneven settlement of elastic supports are considered by means of creep transformed-section method. It is shown that: 1) the strain of tensile steel bars increases slightly, especially at the mid-support section; 2) the compressional strains of steel bars and concrete increase relatively larger under sustained loading, especially at the mid-span section; 3) the theoretical reactions at the side-support increase 7.0% after 1006 days loading, while the measured reactions increase 7.2%; 4) the structure internal force redistribution has great influence on long-term flexure deformation of continuous box girders.