The loading effect of excavation can lead to the deformation of adjacent existing tunnel, which may affect the operation and safety of the tunnel. Therefore it is important to assess the effect of excavation of fundamental pit on the structure safety of adjacent tunnels. Based on the procedure of engineering, the finite element method software Midas GTS NX was adopted for numerical simulation, aiming at conducting assessment on the effect of excavation of dip on the structure safety of subway. The results indicates that the displacement of tunnel around the dip increase as the excavation proceeding. Besides, it is necessary to strengthen the stiffness of the supporting system in the design of excavation can not only ensure the safety of the foundation pit but also better control the deformation of adjacent subway structure. In addition, some other conclusions of the retaining structure in the design of excavations were summarized, which can provide references for the other similar engineering design and construction.