A high-altitude long-endurance aircraft with high-aspect-ratio wing usually generates large deformation,which brings the geometric nonlinear aeroelastic problems.In recent decades,it has become a key focus of the international researchers of aeroelasticity.But some critical technologies are not developed systematically,such as aerodynamic calculation methods of the curved wing with deformation,moreover,there are few experimental validations of these technologies.In this paper,we established the steady aerodynamic calculating method of the curved wing with quite large deformation based on the extended lifting line method,and calculated the unsteady aerodynamics using the strip theory considering curved surface effects.Combining the structure geometrical nonlinear finite element method,we constructed a systematic analytic approach for the static aeroelasticity and flutter of very flexible wing,and further designed the ground vibration and wind tunnel test to verify this approach.Through the test and the theoretic results comparison,we concluded that the extended lifting line method has adaptable precision for the static aeroealsticity and the strip theory considering curved surface effects for flutter analysis can give exact critical speed and flutter mode when the dynamic stall does not happen.The work in this paper shows that the geometric nonlinear aeroelastic analytic approach for very flexible wing has very high efficiency and adaptable precision.It can be used in the engineering applications,especially the iterated design in preliminary stage. A high-altitude long-endurance aircraft with high-aspect-ratio wingially generated large deformation, which brings the geometric nonlinear aeroelastic problems. Recent decades, it has become a key focus of the international researchers of aeroelasticity. But some critical technologies are not developed systematically, such as aerodynamic calculation methods of the curved wing with deformation, moreover, there are few experimental validations of these technologies. In this paper, we established the steady aerodynamic calculating method of the curved wing with quite large deformation based on the extended lifting line method, and calculated the unsteady aerodynamics using the strip theory considering curved surface effects. Combining the structure geometrical nonlinear finite element method, we constructed a systematic analytic approach for the static aeroelasticity and flutter of very flexible wing, and further designed the ground vibration and wind tunnel test to verify this approach.Through the test and the theoretic results comparison, we said that the extended lifting line method has adaptable precision for the static aeroeality and the strip theory considering curved surface effects for flutter analysis can give exact critical speed and flutter mode when the dynamic stall does not happen. The work in this paper shows that the geometric nonlinear aeroelastic analytic approach for very flexible wing has very high efficiency and adaptable precision. It can be used in the engineering applications, especially the iterated design in preliminary stage.