The　great　natural　spatial　variability　whose　expectation　value　decreasing　with　the　soil　depth　can　be　observed　for　saturated　hydraulic　conductivity.　Therefore,　the　local　average　method　is　adopted　to　simulate　the　corresponding　one-dimension　non-stationary　random　field　of　spatial　varied　hydraulic　conductivity　using　Fish　code　in　FLAC.　The　process　of　rainfall　infiltration　is　calculated　using　the　module　of　two-phase　flow.　Within　the　Monte-Carlo　framework,　the　influences　of　variability　of　saturated　hydraulic　conductivity　on　the　distribution　of　the　critical　slip　surface　and　on　the　corresponding　failure　probability　at　different　time-moment　of　rainfall　were　studied,　based　on　the　infinite　slope　stability　model　with　the　effects　of　positive　pore　water　pressure　considered.　The　results　show　that　without　considering　the　variability　of　saturated　hydraulic　conductivity,　the　deterministic　analysis　method　fails　to　represent　the　realistic　slope　stability.　With　the　increase　of　rainfall　duration,　the　probability　of　critical　slip　surface　occurring　at　the　bedrock　of　slope　base　may　decrease;　with　the　increase　of　vertical　correlation　distance　for　saturated　hydraulic　conductivity,　the　probability　of　critical　slip　surface　occurring　at　the　slope　base　may　increase,　but　the　corresponding　failure　probability　of　slope　may　decrease　with　the　increase　of　vertical　correlation　distance.　©　2017,　Editorial　Office　of　China　Civil　Engineering　Journal.　All　right　reserved.