According to the real structure and work condition of a large-scale gas control valve used in recycling generating electricity project, a sequential fluid-structure interaction system model of control valve is set up, the coupling of fluid and valve plug is studied. The complicated fluid pressure, stress and deformation of balanced valve plug and stem at different control valve openings are investigated. The root cause of plug vibration by fluid is revealed. The natural frequency and modes of vibration are obtained, which could verify whether the design overcomes resonance. All of these are in favor of realizing design optimization in fluid-structure interaction and are of great practical significance for advancing study on large-scale control valves.