The construction is difficult in Dacun exploration area in Guxu mining area of South Sichuan coal field with Karst cave and crack development, coal seam collapse and the wall damage by gas pressure test and CBM well test. In order to deal with the above difficulties, the suitable construction processes and technical measures were adopted in borehole structure design, bit selection and the usage of drilling fluid and casing, the good effects ensured the smooth drilling construction in this area.