Objective Porcelain-fused-to-metal (PFM) is widely used in oral clinic because of its intensity of metal and finery of porcelain. However porcelain often flakes off in the interface of metal and porcelain. To investigate this problem,the interfacial intensity of different thickness ratios is studied for analyzing the failure mechanism. Methods Moiré interferometry was applied in experimental study of four-point bending specimens with interfacial crack and no interfacial crack and results of experiment are compared with that of finite element analysis. Results Displacement field and stress field of crack tip are obtained. Simultaneously,fracture density and stress parameter of interface are also calculated. Besides,specimen fabrication process and experimental method are also introduced. Conclusion Because of mid-layer place of metal-porcelain cross section moved along with layer ratio,so it can be concluded that thickness ratio has great influence for fracture intensity.