The homogeneous solutions to the governing difference equations derived from energy variational method were used as the displacement patterns of finite segment. A finite segment model considering the initial curvature, bending,torsion,shear lag and distortion was established. The stiffness matrix and load column matrix were obtained based on the directed stiffness method and the working energy principle. A finite segment method was presented to calculate the shear lag effects with multi-span continuous curved box girder generally used in engineering. A perspex glass model of a two-span continuous curved box girder was made.The test on the perspex model were performed to study the shear lag effects respectively under concentrated load and uniformly distributed load. The calculation results of finite segment method were in agreement with the experimental results and results of finite element method, which verifies the accuracy of the finite segment method.