Abstract: Based on the first piston theory of supersonic aerodynamics, the flutter differential equations of a three dimension panel are set up according to the Von Karman large deformation strain-displacement relation by using a Galerkin approach. The influence of a boundary condition relaxation, in-plane load and length-to-width ratios of panel are analyzed. The results show that with the relaxation of boundary conditions the critical dynamic pressures acting on the panel reduce and the static stability of system decreases, while the probability of buckle and chaos increase as the relaxation of boundary conditions. The results also indicate even though the dynamic pressure is less than the critical dynamic pressure, the panel is likely to experience limit cycle oscillations or chaotic motion as the relaxation of boundary conditions. In addition, the more compression in-plane loads and the lower length-to-width ratio are no beneficial to the flutter stability of the panel.