Abstract: In this paper, taking 311101 working face of Bayangaole Mine as engineering background, using field testing, theoretical calculations and numerical simulation methods, on the basis of revealing abutment pressure distribution laws of large fully mechanized mining face, we study different widths pillar stress field and distribution of plastic zone. Finally, we determine a reasonable section of coal pillar width. Studies show that: when pillar width is 15 to 20 m, there is still a certain elastic nuclear in central coal pillar, coal pillar remains stable. Considering the coal resource recovery and roadway stability and other factors, we determine that the Ordos region fully mechanized mining face of coal pillar reasonable width is 15 m.