Underground rock affected by crustal movement develops various geological structures, fault, as a common geological structure affects the safe recovering mining. Based on characteristics of fault type, small fault with large distribution and difficulty to avoid was taken as study object, 3.3 m fault in 3108 fully mechanized working face of Huasheng Mine was taken as example, the mechanical properties of coal rock change was analyzed, the broken coal body mechanism was given, the distribution of the stress field and the stress under the influence of fault were calculated by FLAC3D, The technology of weak zone elimination of coal rock mass was put forward, the distance and time of overhand mining was settled, avoiding roof caving, strengthening the support of roof, with good technical effect.