Abstract: Aiming at the problem of reasonable narrow coal pillar size of driving roadway along goaf of 6111 deep steep fully-mechanized working face. Based on the limit equilibrium theory solved the coal pillar width and analyzed the stress distribution and deformation characteristics of the roadway surrounding rock by using numerical simulation of FLAC3D, the reasonable narrow coal pillar width was determined and successfully applied to engineering practice．Some conclusions can be drawn as follows:? With the increase of coal pillar width, side of narrow coal pillar appeared the phenomenon of stress concentration and the coal body side stress changes little, vertical and horizontal displacement of roadway changes with different growth;?The engineering practice showed that selected coal pillar in 5m width scientific and reliable which can meet the needs of engineering．