Abstract: To analyze the shear-lag effect of box girder with varied flange depth by bar simulation method, a modified bar simulation model was proposed to consider the effect of corner supports in this paper. A simply supported box-girder beam was taken as an example to discuss the applicability of the modified method in analyzing the shear-lag effect of box girder with corner supports. It is found that the proposed equivalent method of bar area and plane depth is appropriate to be applied in analyzing the shear-lag effect of box girder, and the calculation results of normal stress on a flange near the web are affected by the number of equivalent bars, which is not significant. The theoretical solution of bar simulation method shows good agreement with the numerical solution by using solid finite element method in most regions, except for the region near bearing supports. Comparing the box-girder with uniform flange depth, the corner supports help the web restrict the shear deformation of flange and decreases the shear stress in flange, which weakens the shear-lag effects of box girder.