Based on scientific and effective hard roof key stratum for single working face carrying on problems, took Rongtai Mine 10102 return air lane along the empty left lane as the research object, the method of theoretical analysis and practical analysis was taken, the reserved lane overburden of dynamic and static load and the influence of strata movement, the roof fracture location, the advanced mining supporting effect of the reserved lane were analyzed, which reflected the basic characteristics of roof and established mechanical model, its feasibility study was analyzed. The results showed that the single hard working face roof key stratum along the empty left lane was feasible.