Haixin Bridge with the main arch span of 198m and across the Pearl River in Guangzhou, China, is the longest footbridge in the world. The structure of the bridge is the complicated combination of inclined arch and curved beam, and the bridge deck width is 15m wide consisting of fast and slow passing lanes, so the bridge is flexible and the problem of pedestrian comfort is prominent. In this paper, a refined 3D finite element model of Haixin Bridge is established to determine the natural frequencies falling into the frequency range of walking forces, and then the corresponding walking force models are constructed. By the dynamics analysis, the peak acceleration is obtained and the pedestrian comfort is evaluated by comparing the acceleration with its threshold in the code. Finally, a damping scheme is proposed to install tuned mass dampers (TMDs) to improve the comfort level of the bridge, where the parameters of mass, damping, and stiffness of the dampers are optimally fixed for each sensitive mode.