To improve the accuracy of aerodynamic parameters of membrane structures depending on numerical simulation method, the aerodynamic characteristic of ETFE air-inflated membrane structure on the roof of the National Aquatics Center (NAC) is analyzed based on the hybrid substructure method of on-site monitoring and CFD numerical simulation in this paper. The ETFE air-inflated membrane structure and flow field are considered as two substructures, the vibration response of the ETFE air-inflated membrane structure is measured from the Health Monitoring System of NAC and treated as the moving boundary condition of air-inflated membrane structure in the flow field. Only the flow field around the moving boundary is simulated by the CFD code CFX 11.0. By CFD numerical simulation, the additional mass, aerodynamic damping and aerodynamic force of ETFE are obtained and the changing laws of these aerodynamic parameters with time and wind speed are studied. The research results indicate that the hybrid substructure method of on-site monitoring and CFD numerical simulation is an effective approach to obtain aerodynamic characteristics of air-inflated membrane structure.[JP]