The change of underground formation pressure is crucially related to the complexity of borehole condition. Formation pressure prediction is an important means for borehole design and drilling risk control, and rational prediction of formation pressure is furthest solving complicated difficulties in deep drilling. In recent years, modern techniques of earth stress prediction have been widely explored in academic circle and application field in the world; but the traditional water-pressure test is still the most applicable method due to its simplicity of on-site operation. In this paper, by the case of a deep drilling project in complex formations in Yunnan Province, the rationality and feasibility of formation pressure prediction in wire-line coring drilling activities are verified.