With　the　PDPA　(Phase　Doppler　Particle　Analyzer)　measurement　technology,　the　probability　distributions　of　particle　impact　and　lift-off　velocities　on　bed　surface　and　the　particle　velocity　distributions　at　different　heights　are　detected　in　a　wind　tunnel.　The　results　show　that　the　probability　distribution　of　impact　and　lift-off　velocities　of　sand　grains　can　be　expressed　by　a　log-normal　function,　and　that　of　impact　and　lift-off　angles　complies　with　an　exponential　function.　The　mean　impact　angle　is　between　28　degrees　and　39　degrees,　and　the　mean　lift-off　angle　ranges　from　30　degrees　to　44　degrees.　The　mean　lift-off　velocity　is　0.81-0.9　times　the　mean　impact　velocity.　The　proportion　of　backward-impacting　particles　is　0.05-0.11,　and　that　of　backward-entrained　particles　ranges　from　0.04　to　0.13.　The　probability　distribution　of　particle　horizontal　velocity　at　4　mm　height　is　positive　skew,　the　horizontal　velocity　of　particles　at　20　mm　height　varies　widely,　and　the　variation　of　the　particle　horizontal　velocity　at　80　mm　height　is　less　than　that　at　20　mm　height.　The　probability　distribution　of　particle　vertical　velocity　at　different　heights　can　be　described　as　a　normal　function.