In order to ensure the safety of the adjacent metro tunnels during blasting excavation of foundation trench of the immersed tunnel, the current situation of the metro tunnels are evaluated by field measurement. And then the mechanical response characteristics of the metro tunnels to the blasting excavation of foundation trench are numerically analyzed; and the safety criterion for the existing tunnels as well as the safe distance of the blasting vibration of the immersed tunnel foundation are proposed. The results show that: (1) The accumulated maximum settlement of the existing metro tunnel is 1.89 mm and the maximum settlement rate is 0.01 mm/d in the last half year, which are less than the control values and shows that the tunnel structure is stable. (2) The maximum vibration velocity of the metro tunnel structure caused by blasting vibration of immersed tunnel foundation is 0.359 cm/s, which is significantly less than safe limit 2.0 cm/s and illustrates that the influence of blasting excavation on metro tunnel structure is small; the safe distance of blasting vibration is 25 m. (3) The maximum settlement of the metro tunnels caused by foundation trench excavation is 3.16 mm, which is less than the control value and illustrates that the tunnel structure are in a safe state.