Abstract: Based on upward mining under the conditions of closed and hard roof seam,using integrated approach inclu- ding theoretical calculation and numerical simulation,the mechanical model of suspended structure at the edge of lower goaf was established,and the form and the criterion of secondary instability about the suspended structure were de- rived. The suspended structure,which ensured the continuity of upper coal seam,was conducive to mining the uplink working face,but it’s secondary instability would bring greater safety risk to the mining of the uplink working face. In addition,through analog simulation method,the fracture morphology of stope wall rock during the uplink working face mining was analyzed,and the positive and negative influence of the suspended structure to the process of the uplink working face mining was proved. The research results provide a theoretical basis for the implementation of the safety technology during the uplink working face mining,ultimately,the safe mining of uplink working face was guaranteed.