Numerical simulation research has been conducted in order to reveal the mechanism of the layered fracture within surrounding rock in deep-buried tunnel.Analysis of the history of the rock mass and its environment suggests that the mechanism of the deep rock mass was located in the post-peak stage, the post-peak characteristic indexes and the excavation response equations were selected based on the post-peak stress-strain characters of rock mass.A numerical model was established, a monitoring scheme of surrounding rock response was designed which was caused by excavation, and a fair amount of excavation was completed by numerical simulation method, and the phenomenon of layered fracture within surrounding rock was reproduced in the numerical simulation.According to the monitoring results about the rock stress and deformation distribution from the experiment, and based on the critical conditions under which the layered fracture in surrounding rock was emerged, the relationship of the fracture layer number of surrounding rock, the radius of layered fracture zone and the maximum peak stress with the post-peak characteristic indexes were studied.Based on the surrounding rock stress redistribution related to the excavation of underground structure and the fracture mechanism of rock mechanics, this paper analyzed the mechanical mechanism of the formation of secondary free-surface and multiple excavation surface.The numerical results provide the basis for the layered fracture in deep surrounding rock, and the confusion about the unobserved phenomena of layered fracture in numerical simulation is also eliminated.