Abstract: In order to analyze the influence of the dip angle of the formation on the dredging water from the borehole in the gently inclined strata, a numerical model of groundwater in the combination of gently inclined strata and upward-sloping borehole is established, and the water level and drainage dynamics of the aquifer are simulated under the conditions of setting the inclined borehole as constant-flow and constant-head well boundary. The results show that: in the early stage of the drainage of high-water pressure water-rich aquifer, the water pressure of the aquifer with large dip angle is not easy to drain down when the water discharged from the aquifer is restricted by the drainage capacity of the borehole and kept at a constant flow; in general, aquifers are discharged for a short period of time. When the water pressure at the drilling position drops to its position elevation and the constant head well is kept for drainage, aquifers with larger dip angle have larger water displacement and more significant water pressure relief. When the dip of the formation reaches 25°, the influence of the dip of the formation on the dredging water of the borehole is obvious.