Abstract: Steep stable conditions to ensure the fully mechanized support has been one of production safety problems of steeply inclined working face.Now,according to Lizuizhi coal mine 3232 (3) steeply inclined working face a specific conditions as the research basis,in combination with the related knowledge of theory of inclined masonry structure and theoretical mechanics,to the roof of tilt masonry structure in the tendency of support stability under the action of (decline and dumping) is analyzed with mechanics.The results showed that 3232 (3) working face support working resistance minimum not less than 4023 kN can remain stable,the choice of the 4600 kN support resistance of working face support is quite reasonable.Finally,by analyzing the support mechanical model,raised that in the process of working face advancing,support base mounting base double jack,top beam double jack and technical measures such as changing the moving frame method can effectively adjust and prevent support dumping and decline phenomenon,greatly improve the support stability,guarantee the safe and efficient production of fully mechanized working face.