The thermal-mechanical fatigue behavior of DS superalloy DZ125 was studied.A basic cycle has been used without hold time and with hold time at high temperature to simulate only the transient behavior of critical part of a blade. Both triangular and trapezoidal wave shape signals with in-phase cycle and at maximum and minimum temperature of 550℃and 1000℃ respectively.The ratio Rε of minimum to maximum strain is^-1.0.At the same strain amplitude,it was found from test that the TMF life of in-phase cycle with triangular wave shape is longer than that of in-phase cycle with trapezoidal wave shape.Also the effect of hold time on cyclic stress response under conditions of triangular and trapezoidal wave shape was studied.The thermal-mechanical fatigue damage was discussed. The results show that fatigue,creep and oxidation damage always developed during TMF.Fracture is mainly intergranular and transgranular under conditions of triangular wave shape.The path of crack initiation and growth is transgranular under conditions of trapezoidal wave shape.