The thermo-mechanical fatigue（ TMF） behavior of casting alloy Ti-48 Al-2 Cr-2 Nb was researched. The tests were performed thermo-mechanically in-phase（ IP） at 400℃ ～ 800℃ . During TMF,tests strain was controlled. The result of this IP TMF was compared with 400℃ and 800℃ isothermal low cycle fatigue（ LCF）. The result shows that the fatigue life of Ti-48 Al-2 Cr-2 Nb alloy in 400℃ ～ 800℃ TMF condition is longer than 400℃ and 800℃ LCF within high strain region. Within low strain region,it is slightly shorter than 400℃ LCF and within the dispersion zone of 800℃ LCF. In this TMF condition,no evidence shows hardening or softening phenomenon. SEM analysis shows that inter-lamellar and inner-lamellar cracking and trans-lamellar tearing can be observed on the fracture surface.