Abstract: To solve the Bachmat nonlinear seepage equation, an iterative algorithm based on the variable permeability Darcy seepage isproposed, considering the goaf characters. Finite element numerical model for nonlinear air leakage flowpattern in caving goaf is established, the flow laws (contours of wind pressure andlines of stream function) and the goaf air leakage intensitydistributions (velocity field) are obtained by calculating the air leakageseepage of complex boundary goaf, which are found to be consistent withthe practical flow patterns. The results indicate that the iterativealgorithm converges with oscillation, and the convergence is rapid; incomparison to the Darcy seepage, only the largest wind velocity around thelocal area near the working face for the nonlinear seepage reduces to 0.61of the original value, and there is no significantdifference in other areas.