Abstract: In order to solve the problem that the stability of mining overall height in one time working face of 6.5mthick seal coal.Proposing that the formation and expansion of the coal wall plastic zone and working face bracket supporting strength is two main factors which impact the stability of such working face.Then,combining with Lade-Duncan strength criterion under plane strain condition,Establishing the formula of the coal wall width of plastic zone,at the same time,through the numerical simulation analysis studying the above factors.At last proposing a method that increasing use of stents to help guard plate support resistance and coal wall grouting to control the stability of the coal wall.Field test shows,the methods above solve a technical problem of the stability of Wangzhuang coal which is mining overall height in one time working face.