Abstract: A numerical simulation of a cylindrical system with plasma sprayed thermal barrier coatings under typical thermal loading was conducted,and the failure mechanisms were analyzed based on the stresses in ceramic coat. It is found that,there are two types of interfacial (transverse) cracking patterns of the ceramic coat:in the cooling process,mode Ⅰ is vulnerable to crack at the peak position of the cosine curve,and mode Ⅱ at the middle position; in the heating process,interface edges are introduced into the ceramic coat/substrate system as a result of the vertical cracks emergence,and the ceramic coat will transversely crack at these positions because of the stress concentration effect.