To study effects of deck roughness and large attack angle on vortex-induced vibration, wind tunnel test has been performed. First, deck roughness was obtained in numeric simulation and according to which, the best match sandpapers were selected for the experiment. Tests of bridge section model were performed with different kinds of attack angles and bridge deck roughness. The results show that the vertical and torsional vortex-induced vibration of flat steel box girder with a large aspect ratio increase at the large attack angle. When the bridge locates in the mountains, it is necessary to do bridge section model test at large attack angle. Deck roughness can reduce the vertical and torsional vortex-induced vibration.Deck roughness has influence on vortex-induced vibration which increases correspondingly with the decrease of the attack angle. Response of torsional vortex-induced vibration is more sensitive to deck roughness, and its range is greater than that of vertical vortex-induced vibration. The accuracy of deck roughness affects the reliability of wind tunnel test.