Abstract: In-service equipment is subjected to high temperature and high pressure for a long time and its important mechanical properties cannot be predicted. It is necessary to establish a yield strength model considering high temperature creep damage. The traditional yield criterion ignores the characteristics of temperature influence and the decreasing trend of effective Young 's modulus with damage accumulation. The theoretical model of metal temperature dependent yield strength and K-R creep damage constitutive equation are introduced. On this basis, the internal relationship between the service Young 's modulus and the internal variable of creep damage is established, and the yield strength model of service metal considering high temperature creep damage is derived. The creep interruption combined high temperature tensile test was conducted on SA508-III steel material, and the theoretical calculation was consistent with the test results.