Abstract: In order to determine the rational width of laneway coal pillars for superwide isolated fully mechanized top coal caving face,the abutment pressure and deformation-failure behaviour of different width coal pillars for superwide and common wide isolated fully mechanized top coal caving faces were analyzed by use of numerical simulation software FLAC3D.At the beginning of mining,abutment pressures on the wide coal pillars（20 m in width） decreased with the increase of the distance from laneway coal slide,and increased with the increase of mining distance.The peak value of strike abutment pressures on small coal pillars（4⁶ m in width） increased with the propagation of the working face mining during the initial mining,and the distance of the peak value position to the wall also increased.As for the normal mining,the peak value of abutment pressures would reduce along with the roof deformation and gradually became stable,but the abutment pressures on the coal mass between the peak pressure and the wall would increase.The peak value of abutment pressures on coal pillar had a certain distance to the wall,and the distance reduced when the working face width increased.Lengthening the width of isolated fully mechanized top coal caving face would reduce the abutment pressures for both wide and small coal pillars,and the coal pillar width could be reduced.