In order to effectively reduce the impact of underground tunnel boring on existing building pile foundations, in-depth analysis of the impact of stacked-line shield tunnel boring caused by deformation of adjacent building pile foundations, Foshan Metro Line 3 Nanhai Plaza - stacked Kau interval stacked-line tunnel through the pile foundations of adjacent buildings as the background of the project, the use of Midas GTS NX finite element software, the establishment of a three-dimensional finite element model of the ratio of the length of different piles h to the radius of the tunnel r The three-dimensional finite element model with different pile lengths h and tunnel radius r is used to analyse the displacement impact of the stacked-line shield tunnel construction on the pile foundations of the existing adjacent buildings. By comparing the on-site monitoring data with the model data, the impact of the stacked-line tunnel excavation on the pile foundations of existing neighbouring buildings is obtained under different geometric position relationships. The results of the study show that: when h/r is greater than 7 but less than 10, the total displacement of pile foundation is the smallest; when h/r is less than 7, the total displacement of pile foundation is the largest. When the upper and lower stacked-line tunnels cross the pile foundations of existing buildings, the engineering design should place the axes of the tunnels underneath above the pile base elevation line as far as possible, so as to avoid the loss of bearing capacity at the pile ends due to excavation of the tunnels below the pile base elevation line. The results of this study can provide a reference for the design of similar stacked-line tunnels.