With the development and utilization of underground space and the construction of large quantities of shield tunnels, the phenomenon that shield tunnel go through the existing buildings at close quarters is in the rise. The stiffness mismatch between shield tunnels and existing buildings has a significant impact on the deformation and stress of the connection part. In order to explore the affection on the shield tunnel from the existing buildings while the shield tunnel crosses the later, taken the shield tunnel crossing Wuchang ultra-deep ventilation shaft in Wuhan subway as an example, the influence to the shield tunnel by the existing building is studied. In the sphere of influence, the closer to the ventilation shaft enclosure structures, the more notable the uneven deformation of the tunnel segment structure would be; the closer to the rigid structure, the smaller the transverse bending moment would be; the nearer to the rigid structure, the greater the horizontal axial force, vertical axial force and vertical bending moment would be. The impact on deformation and load-carrying capacity from ventilation shaft enclosure structure on shield tunnel segment weakens sharply by the increasing of their distance.