Abstract: At present, in-situ leaching mining has some disadvantages of lacking reliable design methods, low comprehensive recovery rate of resources and frequent landslide geological disasters. A spherical bare-foot rare earth mine was selected as the research object, and a simplified axisymmetric model of “liquid injection-liquid collection” was established for in-situ leaching. Based on groundwater dynamics and the Dupuit hypothesis, the mine stable infiltration line equation was derived, and the calculation error of the equation was analyzed. The infiltration line equation was expressed as a piecewise function, where the infiltration line in the liquid injection area was the upper half of the elliptic line, and the infiltration line in the non-liquid injection area was a complex shape composed of parabola and logarithmic curve. The error analysis showed that the calculation error gradually increased along the direction of the flow field, and the values of seepage slope, bedrock slope, liquid injection range and relative permeability coefficient had little effect on the calculation error of the infiltration line equation. The equation has good applicability in the in-situ leaching of the spherical barefoot rare earth mine. It can provide a theoretical basis for the “prediction in advance （design)” of the “liquid injection-liquid collection” infiltration link.