Hillslope　failure　usually　occurs　as　soil　resistance　diminishes　by　the　saturation　of　the　soil　layer　during　rainstorms.　Hence,　precise　estimation　of　the　subsurface　flow　movement　on　hillslopes　is　crucial　for　landslide　early　warning.　In　this　study,　the　subsurface　flow　was　analyzed　using　the　kinematic　form　of　Darcy＇s　law　and　solved　by　the　method　of　characteristics.　Analytical　solutions　were　derived　to　describe　the　movement　of　subsurface　flow　on　hillslopes.　A　series　of　tests　with　comprehensible　figures　were　given　to　illustrate　the　time-varying　profile　of　the　subsurface　flow　on　hillslopes　with　different　curvatures　(concave,　straight,　convex)　and　plane　lateral　shapes　(convergent,　parallel,　divergent)　under　prolonged　rainstorms.　We　found　that　the　plane　curvature　was　the　primary　factor　in　controlling　the　hillslope　subsurface　flow.　The　subsurface-flow　discharge　on　the　convex　hillslope　was　larger　than　that　on　the　concave　plane.　Nonetheless,　rainfall　resulted　in　the　fastest　saturation　on　the　concave　plane;　surface　runoff　occurred　shortly　after　the　beginning　of　the　rainstorm.　The　saturation　region　on　the　convex　plane　contracted　quickly　after　the　end　of　the　rainstorm,　and　the　surface　runoff　vanished　simultaneously.　Hence,　the　subsurface　flow　thoroughly　dominated　the　recession.　Moreover,　we　found　that　saturation　may　not　always　initiate　at　the　hillslope　toe.　The　saturation　can　start　at　the　upper　portion　of　the　concave　hillslope　to　result　in　Dunne　overland　flow.