Abstract: Taking the circular roadway of Tangkou Coal Mine as an example, the actual shape and smooth circle of the roadway is used as the geometric boundary conditions. The stress distribution and the plastic zone are calculated by the finite element software ANSYS. The results show that the plastic zone of surrounding rock under smooth excavation boundary is close to the analytical solution based on Drucker-Prager criterion, which is less than the results under irregular excavation boundary; the plastic zone range of local failure of surrounding rock of two sides is 1.33R₀, and the scope of 45 ° direction of the plastic zone is 2.08R₀. Therefore, it is important to consider the stress concentration effect caused by the irregular geometry, which is important for the development of plastic zone near the excavation boundary.