Deep drilling is difficult in Banchang copper polymetallic mining area because of complex stratigraphic structure, strong alteration, fissure development and serious loss of circulation. Series of measures were taken to ensure smooth drilling in the construction process, including optimizing equipments, well structure design and drilling technical parameters, exploring reasonable drilling tools and casing gradation and using plant gum system find-dispersed low solid flushing fluid, which provide the technical support for the subsequent drilling operation and can be feasible experience for deep complex formations drilling.