Abstract: In the process of parallel blasting excavation of two tunnels, the construction of new tunnels will cause different degrees of vibration damage to the linings of the adjacent tunnels due to the small tunnel spacing. In this study, the blasting excavation of a coastal saturated tuff body is taken as the research object, and the vibration effects of blasting excavation of a tunnel under construction on the adjacent existing tunnels are explored. The real-time monitoring of the vibration response of the adjacent tunnels is carried out during the tunnel blasting excavation process, and the numerical simulation of the blasting vibration response is carried out. The results show that in the saturated tuff medium, the dynamic response of the adjacent tunnel to the surrounding hole is the largest at the arch of the blasting side, and the vibration frequency is concentrated in 0~50 Hz. The single-hole charge length and tunnel spacing of peripheral holes should be controlled below 1∶20.