Abstract: The tangential component of the roof load and the support gravitational gravity of the longwall fully mechanized mining face increases with the increasing of the working face angle,while the normal component is opposite,which causes the complicated mechanical environment and degraded steady state control of support on the inclined surface.In particular,the increase in the height of the support,heighten the center of gravity of the support,with the coal wall intensified,and the top of the frame prone to rise and fall,which in turn induces the difficulty of the steady state control of the support,or even the failure,resulting in the collapse of the support or the ultimate overturning.The steady-state control failure of the stent occurred in the 6152 high mining height longwall in steeply dipping seam fully mechanized mining face of Huashan coal mine,which caused the bracket to be seriously dumped and difficult to reset,and the production of the working surface is forced to be interrupted.The dip angle of the support and the working surface is measured on site and the quantitative index—inclination of the support is calculated.The comprehensive analysis results show that the dumping of the support group is mainly caused by the increase of coal seam dip angle,the increase of mining height,the overweight of the support,the inversion and failure of the side guard,the roof topping,the anti-fall and anti-skid device,and the improper operation of the pull support.Based on the characteristics of the rock pressure behavior of the longwall working face in the in steeply dipping seam,the dumping of the support is generally normal distribution.