[en] Creep of a structure which runs for a long time is must be considered, and creep performance of material is also an important mechanical property. Usually, creep limit or creep-rupture strength is used as an index to judge the creep performance of material, but both of them do not apply to the rotor whose stress changes over time. A new and available creep performance index must be established to judge the rotor's reliability. The creep model is transformed into another form, and all models are mapped to a Cartesian coordinate system, so each point in the coordinate plane will present a creep model. Then all models will be calculated whose creep strain equal to design allowed value by finite element analysis. All these models will map into a straight line, and it will be used to determine the material creep performance. (authors)