In this study, an experiment to explore the surface temperature rise of an artificial dry patch at different heating powers was done. Then under specific sizes of the dry patches, the influences of these factors on thermal stress were thoroughly investigated through sensitivity analyses of factors such as the thickness of the heated wall surface, the location of the dry patch, and the thermal conductivity of the heating surface. It is found that in the case of CHF occurrence, even though the local maximum temperature inside the dry patch is much lower than the melting point of the material, the thermal stress caused by the dry patch exceeds the yield strength of the material, which triggers irreversible plastic deformation. Therefore, the heated wall fracture caused by thermal stress will occur prior to wall melting. At the same time, this study also found that changing the thickness of the stainless steel base plate and the thermal conductivity of the material both affect the maximum temperature in the dry patch region. Reducing the thickness of the heating plate makes the temperature in the dry patch region increase, which leads to a dramatic increase in the thermal stresses inside the material. Increasing the thermal conductivity of the material can flatten the temperature field, and the equivalent stresses also decrease.