Abstract: To simplify the aeroelastic analysis by utilizing the general CSD program, an approach to transform the aerodynamic to the desired formation is presented in this paper. For a flow-flexible structure coupling model, the aerodynamic is given in the frequency-domain formula, and then can be expressed as rational polynomials. Through the equivalent transformation, the aerodynamic can be deduced to a second order ordinary differential equation. Then aeroelastic analysis can be achieved under the framework of computational structural dynamics. This approach combined the general CSD program and aerodynamic model, which is derived from numerical analysis or experiment, to simplify the aeroelastic analysis and improve computational efficiency.