The stability analysis of surrounding rock in the tunnel process of construction is a very important research subject of engineering geology and rock mechanics.According to the theory of underground structure design and Druck-Prager yield criterion of rock, Considering the bearing capacity of wall rock itself, the paper analyzed the stability of Yangqu hydropower station spillway tunnel in process of rock excavation construction by use of the method of nonlinear finite element .It also simulated the process of tunnel excavation construction and analyzed the displacement deformation and stress distribution of tunnel surrounding rock.The method can provide the basis for the stability analysis of surrounding rock and structure in the construction of tunnel excavation.