Central Research Institute of Electric Power Industry (CRIEPI) has been conducting a research project on the verification of evaluation method for structural integrity of high-temperature components. As a part of the framework, we developed a flaw evaluation system on PC to predict creep-fatigue crack propagation, which was considered to be an essential crack driving force at high temperature especially in case where stresses caused by thermal loading were significant. The system is featured by easy and dialogical operation with graphical user interface. Fatigue and creep crack propagation behavior can be predicted using fatigue J-integral range and creep J-integral, respectively, which are the variations of the non-linear fracture mechanics parameter, J-integral. Both fatigue J-integral range and creep J-integral are calculated by the reference stress method with revised solutions developed by detailed finite element analysis.