Abstract: In order to completely reveal relationship between surrounding rock and support mechanics in roof-control area, from points of support ability's composition, characters and relative size of stiffness, we discussed the role of support system in relationship mechanics between surrounding rock and support by analytical and comprehensive analysis method. The results show that we will not completely reveal relationship between surrounding rock and support mechanics by ignoring any aspect of the support system. Changing support anti-compression stiffness can significantly affect fracture location of the immediate roof and elastic-plastic zone distribution of top coal caving at mining face .