Abstract:The paper briefly introduced the complex features of hard and broken formation of detailed investigation district in Hongshan iron mine as well as the lithology; summed up the experience of wire-line coring drilling technology in the complex broken formation; emphatically analyzed the treatment of broken & leakage, collapsing & falling and hard & slipping formation in aspects of borehole structure, drilling tools & drilling parameter selection and the flush fluid selection & preparation. The paper also discussed technical measures to ensure coring rate and prevent borehole inclination in complex formation, by wall protection and leaking stoppage, flush fluid ratio improvement, bit matrix hardness adjustment and the improvement of complex formation drilling environment, the drilling efficiency was increased.