Wind-resistant performance of long-span bridges has become one of the important issues in the design of long-span bridges due to complicated meteorological conditions in mountainous areas that will have very negative impacts on long-span bridges in those areas. Methods and results of selecting design wind parameters of the bridges in the mountainous valley are firstly introduced in the paper. Then the process and results of section model tests of the two steel truss bridges are presented. Next a series of optimization tests are conducted aiming at the wind-induced vibration of the main beam and then analysis of all the optimization tests have been made to select the best measure for vibration suppression of the wind-resistance characteristics. It not only meets the need of bridge wind-resistance design, but also can be taken as reference and basis for the design of similar bridge in future.