Abstract: Due to the advantage of overall mechanical performance of concrete box girder, it could be a good choice to solve the problem of limited urban land resources and traffic jam by taking its roof and floor as deck system to achieve double deck traffic. A double traffic concrete box girder model with a scale of 1:6 was designed. Tests under the double uniformly distributed load in elastic state, and bending failure tests under the concentrated load were carried out. The development of stress and strain, load deflection curve of key section, the flexural bearing capacity and failure mode was studied. The results show that there is different shear lag phenomenon under different load conditions in the elastic working state. In double deck concentrated load experiment, the test confirmed the bending process of double traffic concrete box girder with large wide-span ratio and depth-span ratio can be divided into the three phases, i.e., elastic, elastic-plastic and destruction phases. This research is expected to provide experimental data and reference for design and application of double transportation concrete box girder bridge.