Abstract: As one of the most important components in the engine, the structural characteristics and working condition of the rotary blade directly affect the normal operation of the aero-engine. The high-speed rotary blade applied in the aero-engine is taken as the research object, and its buckling instability response is investigated. An analytical model of thermal buckling of rotary blade structure is established to compare and reveal the instability characteristics of linear and nonlinear thermal buckling response of the constrained blade under the temperature field. Comparing the linear/nonlinear thermal buckling response, the nonlinear buckling instability characteristics are found to be closer to the real damage conditions, and the part with the largest buckling stress is analyzed to be located at the root of the blade and is consistent with the experimental comparison, thus obtaining the critical load and its instability conditions of the blade, which is of great significance to reduce the damage of the blade caused by the thermal-structural coupling vibration.