We propose a new coupled method to identify the shape of the interfacial crack between the blade stringer and the skin panel of wing box structural components using embedded fiber Bragg grating (FBG) sensors and to predict the life of the structural components. Our proposed method assumes that FBG sensors are embedded into the interface between the blade stringer and the skin panel of wing box structures. We analyze the data detected by the embedded FBG sensors to identify the shape of the interfacial crack. The numerical simulation of the fatigue growth of the interfacial crack is also presented in this paper. This simulation can express the arbitrary shape of the interfacial crack using the automatic mesh generator. We then apply our proposed identification method to the simulated fatigue crack. The results indicate that the coupled method is useful for the health monitoring of the aircraft structures.