In order to study the ground disturbance and the influence relationship between the two tunnels during the construction of the new shield tunnel undercrossing the existing high-speed railway tunnel, the centrifuge test was used to simulate the construction of the parallel shield tunnel undercrossing the high-speed railway tunnel, and the variation law of the internal force, segment deformation and surface settlement of the existing high-speed railway tunnel undercrossing the shield was studied. It is found that the adverse effects caused by the later tunnel are less than those caused by the first tunnel excavation. For the existing tunnels without settlement joints, the longitudinal settlement of the inverted arch and the vault is U-shaped and anti-U-shaped respectively. The settlement value of the ground surface and the existing tunnel is increased by more than 100%. When the shield passes through the high-speed railway tunnel, the transverse bending strain is larger than the longitudinal, and special attention should be paid at the corner.