To　investigate　the　influences　of　water　saturation　on　dynamic　responses　in　the　unsaturated　ground　under　moving　load,　this　study　derives　Biot　form　governing　equations　for　a　three-phase　unsaturated　medium　that　can　be　easily　solved　using　the　solution　framework　of　a　single-phase　or　double-phase　medium.　The　governing　equations　are　solved　via　two-and-half　dimensional　finite　element　method　(2.5D　FE　method).　A　2.5D　FE　model　of　embankment-unsaturated　ground　system　with　the　consideration　of　node＇s　9　DOFs　(degree　of　freedoms)　is　established.　Through　the　numerical　analysis,　it　is　found　that　when　the　load　speed　is　during　0.5　V-C(min)　to　V-C(min)　(V-C(min)　is　critical　velocity　of　100%　saturated　soil),　the　displacement　responses　at　the　embankment　surface　are　independent　of　the　load　speed　and　only　determined　by　the　product　of　load　speed　and　water　saturation　cS(r).　When　the　load　speed　＜　0.5　V-C(min),　the　displacement　response　amplitudes　are　independent　of　the　load　speed,　mainly　determined　by　the　water　saturation.