Abstract: Applying 2D elastoplastic numerical calculation method and under the conditions of surrounding rock from Grade Ⅲto Ⅴ,it is studied that the characteristics of stress and deformation of middle rock wall in parallelly laid twin tunnel.The research show that stress and deformation of middle rock wall are adverse to parallel tunnel with smaller interval and these locations are very critical for design,construction and monitoring measurements.At the same time,it is also studied that the effects of different buried depth and different reinforcing measures of rock wall on stress and deformation of the tunnels with small interval,which provides guidance to design of support,selection of excavation method,reinforcing method of rock wall and monitoring plans.