Abstract: This paper explored the effects of aerodynamic force and inertial force on the structure deformation of wing by finite element model.The study indicates that the aerodynamic force and inertial force are at the same level.The inertial force of wing has crucial influence on the structure deformation of wing.The maximum deformation was produced by aerodynamic force or resultant force when wing was located horizontally.The study of the structure deformation provides a technical guide for design and optimization of flapping-wing.