Drilling is a direct and effective means for getting geological material. During the drilling period, the complex conditions are frequently encountered such as strata leakage, hole wall collapsing and diameter shrinking, etc. Due to the unstable borehole wall, drill sticking and burying often happen. If it is not timely and properly treated, borehole scrap would be inevitable. In order to get the core fast, safe and accurate, the rule “prevention first, prevention & treatment combination” should be obeyed from the initial design. With the case of Shanggong gold mine, the principle of one level diameter reserved before drilling and drilling with casing & drilling fluid plugging were summarized, which could be the technical reference for the subsequent drilling work.