Abstract: Based on the time domain wind loads obtained by wind field simulation, the nonlinear behaviors of bridge buffeting were investigated by the buffeting analysis method for long-span bridges. In the investigation, a long-span railway cable-stayed bridge was regarded as an example, and both structural geometric nonlinearity and aerodynamic nonlinear factors were taken into account simultaneously. The geometric nonlinear factors include cable sag, beam-column effect and large structure displacement, and the aerodynamic nonlinear factors are wind incidence angle effect and self-excited force. The nonlinear kinetic equation of a bridge structure was solved with the double iteration method. The comparison between linear and nonlinear analysis results shows that the nonlinear factors can result in a great buffeting response of long-span railway cable-stayed bridges.