Abstarct: Nowdays, paying close attention to the effects of tunnel excavation on adjacent structures is of paramount importance, especially when surrounding structures are of great significance. In this research, effort has been made to investigate the effects of excavation of Mashhad Metro line 2 tunnel on the service and emergency tunnel. Mashhad Metro line 2 tunnel is planned to pass just under the service tunnel by a mere distance of 3.7 meters. It goes without saying that service tunnel has been proposed due to the possibility of emergency situation in which even seconds matters. In this project due to technical and environmental reasons, excavation of different parts of the tunnel has been planned by various methods. For example in the proximity of Qa'em Hospital, NATM (New Australian Tunneling Method) has been utilized. According to the fact that the service tunnel is already constructed and it has actually been used for some time, in this study we investigated the effect of the excavation of Line 2 main tunnel on the service tunnel by means of Flac 3D code in 3-dimension mode. The results demonstrate that after complete excavation of line 2 tunnel, induced stress on service and aid tunnel reaches 100 KPa that it is a reason for 0.34 mm subsidence on crown and 5 mm tuck on floor of service and aid tunnel and the maximum subsidence on the ground reaches approx. 47 mm. Since there are 12 steps planned for the excavation, and in each step 1.5 meter of tunnel is excavated. By calculating the percentage of subsidence in each meter of tunnel, it can be said that about half the maximum subsidence is predictable ahead of the tunnel excavation face, about 90% right above the shield and 100% behind the shield. By increasing the pressure of the shield excavation face, For example, if the pressure is doubled, only 9 millimeter of maximum subsidence can be decreased. On the other hand, the effect of increasing the distance between two tunnels was also investigated. If the spacing between two tunnels increased from 3 meters to 9 meters, the maximum subsidence on the ground would be decreased by 11 millimeters.