Abstract: Air-structure coupling vibration is one of the influence factors of blades vibration. In order to study the dynamic characteristics of rotating blades under aerodynamic forces, the CFX and ANSYS were used to calculate the responses of flow field and structure, respectively. The coupling calculation method of blades under air excitation was discussed, and the transient dynamic response of the solid flexible structure was calculated with the blades and air as one system. A rotating blade flow channel model was established to compute the 3D unsteady transient in air flow channel, and the forced responses of blade in different rotate speeds were calculated by importing the transient pneumatic load to the finite element structural computation. The results showed that the blade instability range was near the natural frequency under the unsteady condition. Thus, a feasible method was provided for the estimation and study of the dynamic responses of rotating blades in engineering.