Abstract: Microstructure after long time aging have been observed by means of SEM in GH169 alloys. The results show that the microstructure almost no variation after long time aging up to 5×10⁴h below 650℃, and reveals higher structure stability. However, microstructure is very sensitive to aging temperature beyond 650℃, and there existed complicated phase transformation. The experimental results also show that stress accelerates the complicated phase transformation by observing GH169 gas turbine disk with an engine service life of 2.8×10⁴h