Abstract: A new meth was proposed to study the vibration of a long-span bridge-traffic-wind coupled vibration system considering stochastic characteristics of traffic flow and road surface progressive deterioration. Based on the existing vehicle model, a new three-dimensional vehicle model with 18 degrees-of-freedoms(DOFs) including a longitudinal vibration DOF of the vehicle was presented. An improved CA model considering the influence of the next-nearest neighbor vehicle and a progressive deterioration model for road-roughness are introduced. Based on the equivalent dynamic wheel loading approach, the bridge-traffic-wind coupled equations are established by combining the equations of motion of both the bridge and vehicles using the displacement relationship and interaction force relationship at the patch contact. The numerical results show that the proposed method can rationally simulate the vibration of the bridge-traffic-wind coupled system.