Abstract: For the problem of reasonable layout of mining roadway encountered in lower coal seam mining under residual pillar in a coal mine, through theoretical analysis, numerical simulation and field application, this paper analyzes the floor failure range of residual coal pillar in downward mining of closed distance coal seam and the influence on the stability of lower mining roadway. Based on the theory of soil mechanics and the mechanical properties of 3^-2# coal seam and floor rock, the floor destruction range of residual coal pillar is calculated in this paper, the stress field and plastic zone distribution outer mining roadway of 5m under the residual coal pillar loading are studied by numerical simulation. In addition, a verification analysis was conducted on the excavation roadway of the 33305 working face in the 3^-3# coal seam of a coal mine and the layout rationality of outer roadway of 5 m is finally verified.