The route of new shield tunnel project will pass through the existing MRT station. Then, a new MRT station will be constructed at the intersection of two MRT lines. Moreover, the direct transfer service will be provided between the existing station and the new station. The underground diaphragm wall of new station has been completed adjacent to the existing station. Afterward, the shield tunnel will transversely drive through the existing station and connect with the new station. In order to mitigate the influence on the existing structures, a series of horizontal and vertical ground grouting treatments will be executed underneath the existing station before the launching of TBM. In this research, the 3D numerical software was utilized to analyze and evaluate the influence of tunnel excavation and grouting on the existing structures. The results revealed that the displacements of structures were satisfied to safety standards during the tunnel boring.