Abstract: In order to study the roof support technology of the open-off cut for the fully mechanized coal mining face under the goaf, according to the 6.5 m width 0 pen-off cut of No.3-101 fully mechanized coal mining face in Beiyu Mine, a face roof distance of 0.8 m to above seam goaf and the watery softened floor features of the above goaf, based on the engineering analogy, the W-type steel bands and the 2.5 m long hydraulic swelling anchors were applied to the combined support of the open- off cut of the coal mining face under the above seam goaf.The space between the bolts was 750 mm and the row space between the bolts was 500 00 mm.The two side walls of the open-off cut could not be supported.After the combined roof support technology applied to the site operation, the max relative convergence between the roo f and floor of the open-off cut was 75 mm.Thus the roof support problem of the open-off cut for the fully mechanized coal mining face with a extreme short distance to th e above seam goaf was effectively solved.