This study is a duralumin and applying heat to the STS-wide measurement range is used, the surface temperature by using the temperature of studying the non-destructive testing of a new paradigm to estimate the position and size of a structure defect purpose. STS and duralumin which has a structure defect is applied a heat by a heater. Its difference of STS and duralumin surface temperature is measured using IR thermography. The estimated result of the STS and duralumin experiment and that of theoretical analysis of PDE are compared and analyzed to diagnose the STS and duralumin defect. Moreover, this study can save time and money and improve accuracy contrast to the existing ultrasonic NDE experiment. In addition, the new paradigm of NDT/NDE by reverse-engineering is going to be valid if the data of thermal analysis and temperature distribution from the specifications of many materials is accumulated and verified. In this study, the average surface temperature of the STS in the same heating condition was 4.53 ° K higher than that of duralumin and both of the surface temperature showed an inflection point in the defect 2.5mm.The maximum surface temperature difference was formed on the 2.5mm, and the study proves its reliability because the average surface temperature of the STS and duralumin was 0.74°K, 0.45°K higher than the theoretical surface temperature.