The paper introduced the application of large diameter diamond wire-line coring drilling tool in complex formation of Fengtai ore field and the construction process. According to the problems of collapsing and block falling in borehole, low construction efficiency, difficult coring and low quality of construction, with the effective measures of drilling method, borehole structure, borehole protection, drilling parameter, reducing resistance by lubrication and drilling tool grading, the efficiency of drilling construction and engineering quality were improved.