Abstract: During the acceleration test run of an aero-engine, the gas turbine working blades fractured. Through macro and micro observations of the fractured blades, fracture surface analysis, metallographic structure inspection, chemical composition testing, as well as aerodynamic stress and strength analysis, the results show that necking occurred in the middle of the blade body of the gas turbine working blades. In the high-temperature zone, the microstructure exhibits rafting of the γ′phase with low content, and partial dissolution has occurred. During the test run, the temperature in the middle of the blades exceeded the allowable limit. Overheating or overburning is the main factor causing blade deformation and cracking, belonging to a combined failure mode of over-temperature creep and overload.