The　probability　distribution　of　lift-off　velocity　of　the　saltating　grains　is　a　bridge　to　linking　microscopic　and　macroscopic　research　of　aeolian　sand　transport.　The　lift-off　parameters　of　saltating　grains　(i.e.,　the　horizontal　and　vertical　lift-off　velocities,　resultant　lift-off　velocity,　and　lift-off　angle)　in　a　wind　tunnel　are　measured　by　using　a　Phase　Doppler　Particle　Analyzer　(PDPA).　The　experimental　results　show　that　the　probability　distribution　of　horizontal　lift-off　velocity　of　saltating　particles　on　a　bed　surface　is　a　normal　function,　and　that　of　vertical　lift-off　velocity　is　an　exponential　function.　The　probability　distribution　of　resultant　lift-off　velocity　of　saltating　grains　can　be　expressed　as　a　log-normal　function,　and　that　of　lift-off　angle　complies　with　an　exponential　function.　A　numerical　model　for　the　vertical　distribution　of　aeolian　mass　flux　based　on　the　probability　distribution　of　lift-off　velocity　is　established.　The　simulation　gives　a　sand　mass　flux　distribution　which　is　consistent　with　the　field　data　of　Namikas　(Namikas,　S.L.,　2003.　Field　measurement　and　numerical　modelling　of　acolian　mass　flux　distributions　on　a　sandy　beach,　Sedimentology　50,　303-326).　Therefore,　these　findings　are　helpful　to　further　understand　the　probability　characteristics　of　lift-off　grains　in　aeolian　sand　transport.　(c)　2007　Elsevier　B.V.　All　rights　reserved.