Abstract: In some horizontal shale oil wells, the wellbore can meet the pressure-bearing requirement, but conventional fracturing tools fails to run in them due to casing deformation. To effectively pack the fractured intervals, the technology of staged sand filling fracturing in horizontal wells was adopted and extreme sand filling was used to form sand plugs in the fractures. Two sand filling modes, which included tail sand filling and fracture blowing, were formed to avoid introducing new equipments. In the Platform Hua H40 of the Changqing Oilfield, tests of staged sand filling fracturing were conducted in the horizontal shale oil wells with deformed casings. Eight stages were fractured by sand filling and the fracturing pressure varied at each stage, with good plugging results and a successful treatment operation rate of 100%. The field results demonstrate that sand filling is dominated by tail sand filling and assisted by fracture blowing, and sand plugs in the fractures can be formed to effectively isolate the fractured intervals. Finally, the staged fracturing of horizontal shale oil wells with deformed casings can be achieved, thereby solving the failure of running conventional fracturing tools.