Abstract: The coupled algorithm between computational fluid dynamics(CFD) and computational structural dynamics (CSD) referring to nonlinearaeroelasticity are studied in time domain. Based on CR (Corotational)theory, the expressions of tangent stiffness equations and internal forcesof 3D shell element under geometric nonlinear structure are derived, thenintroducing a predictor-corrector procedure, a nonlinear dynamic solutionalgorithm is developed based on approximate energy conservation during thedynamic process. Combined with dual-time marching scheme and geometricconservation law, which are included in the solver of Reynolds averagedNavier-Stokes equation, an coupled algorithm is improved for nonlinearaeroelasticity based on the staggered process with mid-steps. The developednonlinear structural solver is performed on static and dynamic analysis andvalidated by the results of experiments and references. With the applicationon nonlinear aeroelastic respones simulation of AGARD 445.6 wing, it showsthat the improved coupled algorithm has a better stability andpracticability for nonlinear analysis.