Landscape in mountainous-valley is complex. Determining the parameters of the wind field is a prominent problem in the design of the bridge. However the existing wind-resistant specification for bridges lacks descriptions as terrain conditions. Based on a real bridge as the engineering background，it carries out a wind tunnel test on the valley of the bridge site. According to the test data，the average wind and fluctuating wind characteristics of different wind directions are analyzed. On the basis of historical wind speed record on the weather station and wind speed standard in specification，the method of calculating basic wind speed at the bridge site area with the gradient wind height and t basic wind pressure is summarized. The experiment results prove that there is no obvious valley-wind effect in bridge site and the mean wind profile cannot be simulated as a uniform. The wind profile exponent is α=0.20 which type of surface is classified into C. Turbulence intensity of the flow down valley center is significantly smaller than others. The measured wind power spectrum compared with the theoretical curve is lower in low frequency and higher in high frequency，its horizontal turbulence power spectrum will shift to high frequency along with the increase of wind direction.