Abstract: An AFT oxidation fan room is a kind of composite structure of reinforced concrete structure supporting the steel tank in the desulfurization process. It is a common structural form of a power plant. The obvious vibration generated by the structure is not conducive to the normal production and operation of the power plant and may even cause accidents. Therefore, on-site monitoring and a simulation calculation are carried out for the AFT structure to study the causes of vibration of the AFT structure and clarify its vibration mechanism. First, a field investigation of the AFT structure is carried out combining video monitoring and local structure vibration monitoring. Based on the simulation method of the fluid-solid interaction, a simulation method to simplify the action of the mixer and the oxidation wind in the steel tank is then proposed, and the vibration characteristics of the AFT structure are further studied through the proposed numerical simulation method. Finally, numerical simulation results are compared with the monitoring results, and causes of vibration differences in various parts of the structure are studied. Results show that video monitoring can quickly identify the structure movement track. Local monitoring results show that the mixer is the main factor of the structural vibration, and the aeration of the oxidation wind intensifies the structural vibration response, causing different degrees of damage to the infill wall between the columns of the structure. The dynamic response law of different positions of each column and the upper steel tank of the structure is found to be more different. A comparison of numerical simulation results with monitoring results verified the calculation method of simplifying the mixer and the oxidation wind effect, providing a reference for the analysis of the vibration response, damage mechanism, and reinforcement design of such structures.