The　unsaturated　seepage　problem　involves　many　fields,　such　as　geotechnical　engineering,　hydraulic　engineering　and　environmental　engineering.　So　it　is　of　great　significance　to　simulate　the　unsaturated　flow　reasonably　and　effectively.　Based　on　the　cover　system　of　numerical　manifold　method　(NMM),　a　NMM　discrete　form　is　established　to　solve　the　Richards　equation　for　the　unsaturated　flow.　Compared　with　finite　element　method　(FEM),　NMM　is　more　flexible　in　the　preprocessing,　and　more　adaptable　to　complex　boundary　conditions.　By　introducing　the　under-relaxation　technique　and　the　lumped　mass　matrix,　the　numerical　oscillation　is　eliminated.　Through　the　simulations　of　1D　and　2D　unsaturated　seepage　problems,　the　validity　and　reliability　of　the　proposed　algorithm　are　verified.　©　2019,　Editorial　Office　of　Chinese　Journal　of　Geotechnical　Engineering.　All　right　reserved.