The Nanchang Metro Line 2 has an ultra-small distance segment on the east bank of the Ganjiang River. The impact of ultra-small clearance on the two-line construction is still unclear. In this paper, the nu- merical simulation analysis of the ultra-small distance segments of two tunnels is carried out by the 3D solid e- lastoplastic model. The results show that the total stress on the central axis of the tunnel lining is the largest; the new tunnel excavation has a hysteresis for the deformation disturbance of the pre-built tunnel; the maximum dis- placement occurs behind the excavation section, and the maximum limit of excavation disturbance exists; The tunneling makes the deformation of the pre-built tunnel lining up to the horizontal axis above the excavation side and the maximum stress increment, showing the phenomenon of bending to the excavation side. If it is necessary to strengthen the stratum, the area can be considered. The internal force disturbance of the tunnel is advanced, that is, the internal force increment of the tunnel within a certain distance in front of the excavation face is the largest.