The stress distribution and its evolution，after repeated thermal shock, in NiCrAlY coatings/YSZ diffusion barrier /René N5 substrate were studied using the finite element method, as well as the effect of peak value on stress. The results showed that higher shear and tensile stresses existed in the outer edge and the alumina layer, where cracks were easier to initiate and propagate, after 75 times- thermal shock. With the increasing number of thermal shock, the stresses in YSZ active diffusion barrier coating system increased. Moreover, the peak stress increasement was observed in the alumina layer, and the optimum peak value (A) was 3 μm.