Several nondestructive evaluation methods were attempted for the estimation of the creep damage of degraded 2.25Cr-1Mo steel. The specimens of three different aging periods were prepared by an isothermal heat treatment at 430°C, 482°C, and 515°C. The effect of probe configuration on the electrical resistivity was studied. Single configuration method and dual-configuration method were utilized for measuring electrical resistivity. The electrical resistivity was determined by a standard DC four-point probe method at 24±0.5°C. Indentation test, magnetic characteristics test and ultrasonic test were carried out to investigate the correlation between the major characteristics and aging parameter. Unlike the electrical resistivity characteristics, ultrasonic attenuation coefficient and indentation characteristics did not show a relation to Larson-Miller parameter. However, a correlation between the electrical resistivity and aging parameter was identified, which allows one to estimate the extent of material degradation.