The influence of the construction of a mining tunnel on NanjingHexian intercity railway crossing underneath an existing NanjingWuhu freight railway tunnel is analyzed by means of numerical simulation, so as to verify the rationality of the design of the mining tunnel and the safety of the existing freight railway tunnel. The results show that, after the construction of the mining tunnel, the maximum settlement of the existing railway tunnel is 6.7 mm, the maximum horizontal displacement of the existing railway tunnel is 1.2 mm and the maximum additional bending moment induced is 32 kN•m. The deformation values can meet the operation requirements of the existing freight railway and the internal forces are within the design scope of the structures. It is verified that the ground reinforcement measures including “directional piperoof + forepoling” taken are reliable, and the design of the mining tunnel crossing underneath the existing railway tunnel is rational. The paper can provide reference for similar projects in the future.