Based on the approaching construction of viaduct and shield tunnel, the effect on viaduct and shield tunnel has been evaluated for the construction scheme and the measures have been taken for the risk in the process of construction. The three-dimensional numerical simulation and procedure of approaching construction are established by using MIDAS / GTS finite element analysis software. Deformation of key nodes in numerical simulation are studied for meeting regulatory requirements. Combined with similarity engineering, important points are proposed in the construction process of approaching construction of viaduct and shield tunnel. The research results indicate that after the construction of the upper structure of the bridge, the vertical deformation value of the interval is positively correlated with the distance between the interval structure and the bridge pile foundation, which gives the reference for the approaching construction.