The geological conditions of Hadamen mining area in Inner Mongolia are complex， and the upper and lower plates of the ore seam in the area are chlorite and petrified alteration belts， with a thickness of tens of meters to hundreds of meters， involving crushing， leakage and water-sensitive strata， and the phenomenon of diameter reduction， leakage and collapse in drilling construction is common， which seriously affects the drilling efficiency. Taking the ZK20312 drilling hole in the mining area as an example， after two waste holes， combined with the drilling difficulties， targeted solutions were proposed， and good results were achieved in the third construction through scientific design of the hole body structure， reasonable allocation of flushing fluid， and reasonable formulation of accident response measures in the hole， and all quality indicators met the design requirements. The construction experience of this type of complex formation is comprehensively summarized， which can provide reference for other similar conditions.