Abstract: To study the influence of ground surface roughness on wind environment over bridge site, numerical simulation of the wind speed profiles at the mid-span position in both ideal and real gorge model are carried out by employing Computational Fluid Dynamics Method. According to the analysis of the ideal model, the general law of wind profiles under different roughness is obtained and the characteristics of wind environment in gorge are analyzed. Based on the analysis of the wind field, the causes of roughness' influences on wind profiles are revealed. The conclusions are verified in the real gorge terrain model and the roughness distribution is optimized according to the land type. It is showed that in gorge area, the influences of roughness on the wind profiles are essentially different from that in regular area. With the increase of roughness, the wind speed may increase at the height of bridge deck. The research conclusions provide a basis for the determination of design wind speed of the bridge in complex terrain.