Abstract: The influence of phase on thermal mechanical fatigue life is discussed by comparing with three different kinds of the phenomenological descriptions of the life curves which are expressed in terms of mechanical strain range Δε_m, total strain range Δε_t and inelastical strain range Δε_in respectively. And the simplified laboratory thermal mechanical fatigue test method which is subsequently undertaken to simulate the service conditions of engineering materials and the working conditions of the turbine disk. It is show that the terms of total strain range Δε_t must be used not only in test but also in phenomenological describing the life curve for thermal mechanical fatigue.