Sintering and mixed oxide (MO) growth significantly affect the thermal and mechanical properties of thermal barrier coating system (TBCs) in gas turbine at high temperature. In this work, we numerically analyzed the effects of sintering and MO growth on the interface cracking of TBCs. A thermal-elastoviscoplastic constitutive model was introduced, in which the effect of sintering was studied using a spherical shell model. Based on the same spherical shell model and our previous experimental observations, we theoretically derived the evolution of relative density and applied this constitutive model to the sintering of ceramic coating. The numerical results showed that viscosity, initial porosity of ceramic and the growth rate of MO had significant effects on interface cracking. In contrast, the influence of initial pore size of ceramic coating was neglectable. Suggestions were also made for the choice of material during TBCs design. (C) 2015 Elsevier B.V. All rights reserved.