The purpose of this paper is to develop a procedure for obtaining the dynamic response of thin-walled curved box girder bridges due to truck loading and to get their basic impact characteristics. The box girder bridge is divided into a number of thin-walled beam elements. Both warping torsion and distortion are considered in the study. The analytical vehicle is the AASHTO HS20-44 truck simulated as a nonlinear vehicle model with 11 independent degrees of freedom. Four dierent classes of road-surface roughness generated from power spectral density function for very good, good, average, and poor roads are used in the analysis. In comparison with the other approaches developed by former investigators, the proposed procedure not only facilitates a physical understanding of the general structural response, but also greatly reduces the computing time required and output obtained. The analytical results show that most impact factors of torsion and distortion are much larger than those of vertical bending response. The impact factors of normal stress at dierent points in the same cross section are quite dierent. The larger the normal stress, the smaller the impact factor will be. Though the static normal stresses at dierent positions in the same cross section may be extremely dierent for a curved box girder bridge, their dynamic normal stresses tend to be uniform.