Based on the analysis of rules of strata behavior and characteristics of rock movement,the interactional relationship of "support-surrounding" for deeply dipping full-mechanized coal mining face was put forward.The support-system stability in fully mechanized coal mining face for steeply dipping seam was analyzed.Taking the 56104 coal mining face of Xinzhuangzi Mine as the practical example,the paper mainly introduces the key technical measures such as the stability control of roof and floor as well as the structural parameters of supports.