Abstract: The aerodynamic force, the fluctuating pressure, and the structural vibration together constitute a multi-field coupled system with complicated interactions, which poses an extremely challenging problem for the dynamic analysis. With the PCL and DMAP languages, a program for analyzing the aerodynamic force- fluctuating pressure- structure coupled response is developed. For an air rudder made of composite materials, a finite element model is established, and the modal analyses are carried out. An aerodynamic model based on the Van Dyke updated piston theory is established. The dynamic response of the air rudder with consideration of the coupling effect of aerodynamic force- fluctuating pressure- structure is obtained based on the modal analyses. Then the results are compared with the uncoupled response of the air rudder under the fluctuating pressure condition leaving out the coupling effect of the aerodynamic force. The influence of the aerodynamic force on the dynamic response of the air rudder is explored. It is indicated that due to the additional aeroelastic effect, the air rudder would shift from the random vibration to a high-order motion way in a pattern of diffused limit cycle oscillations (LCOs), and thus remarkably alter the spectrum of the fluctuating pressure response. It can therefore be said that the aeroelastic effect should be considered in the acoustic fatigue analysis for structures.