Abstract: Well SDCK1 is located in Shuangyushi block, Sichuan area, the upper strata of Shuangyushi block has the characteristics of uneven in hardness, poor drillability, and the lithology contains sand, mudstone and gravel. In the drilling process of ultra-large hole of SDCK1, there are five major problems such as high safety risk of drilling tool, low cleaning efficiency of borehole, difficult quality control of borehole, fast wear of PDC bit and difficulty in casing running. Thus, the research on drilling tool safety guarantee technology, optimization technology of wellbore cleaning in super-sized hole, anti-erosion VMWD tool, comprehensive ROP increase technology and optimization technology of oversize and overweight casing running measures in super-sized hole drilling has been carried out, and the safe and efficient drilling technology of super-sized hole in Well SDCK1 has been formed. The technology was applied in the SDCK1 well in ϕ812.8 mm and ϕ593.7 mm super-sized hole, which effectively ensures the safety of the drilling tool, the cleanliness of the wellbore, and the well quality control is excellent (deviation angle is no more than 1°). Travel footage and ROP are effectively raised, and the heavy casing is running smoothly. The safe and efficient drilling technology of super-sized hole in Well SDCK1 greatly saves the drilling cost. This technology provides technical support for safe and efficient drilling in ultra-large hole in Sichuan area.