The　physical　and　mechanical　behavior　of　alpine　meadow　in　Tibetan　Plateau　is　now　attracting　widespread　attention.　In　this　paper,　a　series　of　experiments　were　conducted　to　study　the　influence　of　roots　on　hydrothermal　behavior　of　alpine　meadow　located　at　Nangqian　district,　in　the　east　of　Tibetan　Plateau,　China.　Root　biomass,　physical　properties　and　hydrothermal　properties　were　measured　at　a　soil　depth　of　0-25　cm.　The　results　showed　that　the　root　biomass　within　the　depth　of　0-15　cm　accounts　for　86%　of　the　total　root　biomass.　With　the　increase　of　soil　depth,　the　root　biomass　shows　a　decreasing　trend.　The　hydraulic　conductivities　and　thermal　conductivities　of　alpine　meadow　soil　increase　with　the　decrease　of　root　biomass.　There　are　lower　hydraulic　conductivity　and　thermal　conductivity　of　swallow　soil　(0-5　cm)　than　that　of　deep　layer　soil.　For　the　bottom　soil　layer,　swallow　alpine　meadow　acts　as　a　＂cap　＂　and　plays　a　function　of　ecological　barrier　of　reducing　water　infiltration　and　heat　transfer.　Under　the　background　of　global　warming,　this　insight　is　helpful　to　understand　the　relationship　between　soil　hydrothermal　properties　and　natural　disasters　in　Tibetan　Plateau.