A damage-based creep constitutive model for a wide stress range is applied to the creep analysis of a 1000 MW ultrasupercritical steam turbine, the inlet steam of which reaches 600 °C and 35 MPa. In this model, the effect of complex multiaxial stress and the nonlinear evolution of damage are considered. To this end, the model was implemented into the commercial software abaqus using a user-defined material subroutine code. The temperature-dependent material constants were identified from the experimental data of advanced heat resistant steels using curve fitting approaches. A comparison of the simulated and the measured results showed that they reached an acceptable agreement. The results of the creep analysis illustrated that the proposed approach explains the basic features of stress redistribution and the damage evolution in the steam turbine rotor over a wide range of stresses and temperatures.