Abstract: According to the standard load cycle spectrum,a stress analysis of 1st turbine disk in an aeroengine was completed to determine its useful life.The places,where the centre hole came across the pin holes,were the dangerous points (so called check points).An experimental rotor of the 1st turbine disk had been designed to model the stress spectrum on the check points.The high temperature LCF(low cycle fatigue)test of an old disk was also conducted at SB804-the disk LCF tester in GTE(Gas Turbine Establishment).The test indicated that cracks emerged on the check points of 5 from all of 16 pin holes on the old disk as the 6047th cycle was completed and the crack extended life is 2886 cycles.The comparative analysis of the test results of the old and new disks indicates that LCF crack growth life and fault life with reliability 99 87% and degree of confidence 95% for the 1st turbine disk are 1132 cycles and 2072 cycles respectively.