Abstract: Based on a practical problem of the teeth crack breakdown of a turbine disc at elevated temperature, an experiment and theoretical study on L-HCCF (Low and High Cycle Combined Fatigue) of fir-tree slot is carried out.The major cause of the fracture is the interreaction of high and low cycle fatigue. Further studies including contrast experiments of light and serious corrosion disc slot are also conducted. Major service factors are successfully simulated and the experiment results show obvious fatigue failure feature which is identical with that in service. A new designed test system, achieving low and high cycle noninterfering loading, high frequency induction local heating ,and the control of high cycle vibration frequency and amplitude,and the crack propagation real-time detection,is established for all above purpose. This investigation is very helpful in establishing the failure standards of turbine disc's slot with corrosion.