Abstract: Inertia force and aerodynamic force are often coupled in flapping motion. In order to study the aerodynamic characteristics of a bat flexible membrane wing in flapping motion, it is necessary to separate the inertia force and the aerodynamic force to obtain the aerodynamic force. By setting up a photographic platform based on multi-vision, images of flexible membrane wings with different properties were captured, and a multi-vision algorithm was used to reconstruct the deformation of the flexible membrane wing, so the inertia force can be calculated from the deformation. A six-axis force sensor was used to obtain the real-time force of the flexible membrane wing, then the aerodynamic force can be obtained by eliminating the inertia force, and the law between the inertia force and the aerodynamic force was analyzed. A standard model verifies that the deformation error of this method is 2.36%. The results show that the highly flexible wing membrane has a significant deformation during the flapping process, which is related to both inertia force and aerodynamic force. And with the increase of the thickness of the wing membrane, the inertia force and the aerodynamic force are increased to different extents.