Abstract: This paper took+735fully mechanized caving face of Dahuangshan coal mine as researched object,and analyzed its surrounding rock control characteristic and the failure mechanism,and then classified the fracture development degree of its surrounding rock.Furthermore,the loading-beam mechanical model of the coal body in anchoring area with large span and thick coal roof was established.And,by means of elastic,structure and materials mechanics,the limit conditions of unbroken state with tensile force was deduced.Sectional countermeasures in gradational loading area were put forward and the specified measures and working effect were analyzed in detail.The field support practice shows that "loading grade" anchor(cable)enhanced support system achieves good control effects on cut open-off with large span and thick coal roof and proves its stability in service period,which also provides technical support for the cut open-off with similar conditions.