Abstract: Previous studies ignored the possible contribution of the yellow clay interlayer to the failure mechanism of Carsington earth dam, and these studies were mainly based on conventional finite element method, which can neither describe discontinuous displacement field such as shear band visually, nor be able to investigate the formation of shear band and the evolution of the mechanics behavior of soils. In this paper, a self-developed simulation system for the evolution of shear band in soil based on the extended finite element method is applied to simulate the failure process of Carsington dam. The results show that the simulation system is able to trace the path and evolution of shear band in the central core of Carsington dam, and reveales the failure mechanism of Carsington dam reasonably, which proves the applicability of this simulation system in complicated structures and stress conditions.