An integrated computational fluid dynamics and computational structural dynamics approach was developed here for simulating the flutter problems efficiently and accurately.The flow solver is based on an implicit time-marching algorithm on multiblock structured grids.The CSD solver adopts the Newmark method to integrate the structural dynamic equations expressed in the modal space.By alternately solving the flow equations and the modal structural equations in the subiteration process,high-accuracy solutions at each physical time step can be obtained.This strongly coupled fluid-structure approach can be used to simulate the flutter and limit cycle oscillation(LCO)problems of an aeroelastic system,which respectively aim at predicting the aeroelastic stability and aerodynamic nonlinearity.In this work,the LCO charateristics of a NACA 64A010 airfoil model were investigated and compared with the literature data.The flutter boundary of AGARD wing 445.6 exhibited a distinct transonic dip which agreed well with the experiment and literature data.In addition,temporal accuracy of the coupled approach and the comparison of flutter responses obtained from different coupling algorithms were also analyzed.