The inside oblique angle between the vertical plane and the arch rib has been shown to be one of the main factors influencing dynamic properties of long-span steel-box basket-handle arch bridges. Details related to the extent, that the inside oblique angle influenced the dynamic characteristics and the seismic response of the arch bridge under the combined longitudinal and vertical seismic excitation and under the combined lateral and vertical seismic excitation, were reported herein. Four oblique angles (0°, 3°, 4.8°, and 6°) were selected based on the arch ribs height and bridge deck width. Findings suggested that a larger inside oblique angle increased the structural stiffness and thus the part internal forces when subjected to seismic excitation. These findings also showed that, when similar structures were designed and seismic considerations were warranted, a suitable inside oblique angle to mitigate dynamic effects should be selected only using a comprehensive analysis. At the same time, traveling wave effect analysis indicated that it couldn’t be ignored when calculating the seismic response of long-span steel-box basket-handle arch bridges
