Abstract: The metro tunnel of a newly constructed line that crosses underneath the tunnel of the existing line in Beijing has significant effects on the adjacent tunnels.Based on the FLAC^3D numerical model and the stress release method,concerning on the settlement slot of the existing metro tunnel and steel tube pre-reinforced construction of the newly constructed line,the process of tunneling is simulated and the settlement of the influenced part of the existing line is obtained.The result is analyzed subsequently.The conclusions of this paper may help evaluate the security of the existing metro tunnel,control the construction process,and actu- alize the monitoring during tunneling.