The Well Mengsudi-1 is a large-diameter key oil and gas geological survey well deployed by China Geological Survey in the Aaitegle Sag， Yingen-Ejinaqi Basin. In view of the geological conditions and technical difficulties in drilling in this block， optimization has been made for the drilling works of the Well Mengsudi-1 from the aspects of the wellbore structure， the drilling assembly， bit type selection and drilling technology. A drilling technical plan with the combination of “simplified wellbore structure+unconventional drilling assembly+conventional bit selection+strong inhibitory mud” was adopted and eliminated a series of problems such as high hardness， poor drillability， easy well deviation and wellbore instability in fractures in Mesozoic Bayingebi Formation and Upper Permian， leading to the successful completion of the Well Mengsudi-1. Drilling of the well was completed at 2763.66m with the diameter of 215.9mm， and the average drilling rate of 3.51m/h. The well successfully revealed the characteristics of Mesozoic and Carboniferous Permian rock assemblages and oil and gas potential， meeting various objectives and tasks with high quality， high efficiency and zero accidents.