A validity criterion of thermal barrier coating was developed by theoretical derivation based on a simplified heat transfer model of turbine blades with thermal barrier coating. Besides

the effectiveness of thermal protection was analyzed based on the validity criterion and engineering practice. Theoretical analysis and numerical experiments showed that the change of composite heat transfer coefficient caused by thermal barrier coating could greatly affect the thermal protection effect. For the front edge of the high pressure turbine blade in the high temperature zone

the maximum rate of change of the composite heat transfer coefficient caused by the thermal barrier coating should be range from 1.25% to 10.83% to meet the thermal protection effectiveness. In practice

special attention should be paid to the change of the composite heat transfer coefficient due to the application of the thermal barrier coating

otherwise it will cause thermal protection failure or even counter effect.