In this paper, a finite element modeling method based on biological observation is proposed, which can construct a finite element model that conforms to the structural strength characteristics of insect wings. A fast and accurate simulation of large deformation motions in anisotropic complex models is realized by establishing a fluid–structure coupling model based on the Lattice-Boltzmann Method and the Central Difference Method. By analyzing the effect of flexible wing deformation on the aerodynamic performance during the flapping process of dragonfly forewing, a physical mechanism to improve the aerodynamic performance of flapping wings is generalized as the chordwise bending mechanism: flexible wing generates chordwise bending during mid-downstroke, which prevents the destruction of the leading-edge vortex structure by the high-pressure region of the flow field, allowing the leading-edge vortex attached to the wing surface, which is conducive to stable lift generation. This mechanism can provide theoretical guidance and data support for the design of wings for micro aerial vehicles.