Abstract: The frequency of structures is an important dynamic characteristic. For aircrafts, when the wing and other large scale structures deform under the action of unsteady aerodynamic forces, its frequency correspondingly changes. For large structural flexible aircraft represented by high altitude long endurance UAVs, it is very important to explore the variation rules of the structural dynamic characteristics of the aircraft to develop the design technology and improve the design method. This paper introduces a test method of a ground electromagnetic dry wind tunnel. A principle experiment method of the ground electromagnetic dry wind tunnel is established. The electromagnetic field and Ampere force are used to realize the simulation of aerodynamics force, and the model is statically and dynamically loaded without touching the model. Based on this new test technique, a series of experiments were carried out by using the experimental system, and the influence of the structural quality and stiffness distribution was analyzed on the internal load of the aircraft under static and dynamic conditions. The results show that the bending deformation affects the bending and torsion frequencies of the structure, and the dynamic characteristics of the structure. This new test method is conducive to the study of aeroelastic characteristics of large flexible structures, and is of great significance for the design and development of new aircraft.