Abstract: In order to determine the rational width of section coal pillar at fully mechanized coal face of close-distance seams in Mugua mine,based on mine pressure and rock control theory,the triangle block structural mechanics model of the lateral rock fracture is established,and the fracture length of old roof along the working face and the fracture span of lateral direction is 11.9 m,and triangle block in the position of coal fracture is 11.5 m.And the numerical simulation method is applied to establish stope 3-D mechanics model,and lateral abutment pressure peak is 20 MPa,stress concentration factor is 2.55 and plastic zone is 10 m with the advancing of stope.Finally,coal pillar reasonable width of 18 m is determined.Field testing shows that fully mechanized coal face has less influence on mining roadway.