Aiming at the problem of large deformation geometric nonlinearity of high aspect ratio wing/multi external storage system affected by aerodynamic, multi external storage and gravity loads, the nonlinear aeroelastic motion equation of wing is established by using medium deformation beam theory and quasi steady aerodynamic model, and the effects of geometric nonlinear deformation of high aspect ratio wing/multi external storage system on structural modal frequency Influence of vibration mode and flutter characteristics.The analysis results show that the influence of geometric nonlinear effect is mainly reflected in the first-order mode of lead-lag, and its flutter mechanism is flexural torsional coupling flutter dominated by the first-order mode of lead-lag. The random wing/multi plug-in system changes from vertical downward bending state to horizontal state, the influence of geometric nonlinear effect is weakened, and the amplitude of the first-order mode shape of lead-lag increases, Moreover, the variation trend of the first-order lead-lag and torsional modal frequencies slows down, which correspondingly reduces the variation amplitude of flutter velocity at the corresponding angle of attack, which shows that it has a certain positive effect on the flutter velocity by slowing down the geometric nonlinearity of the wing/multi plug-in system.