Abstract: The most crowded and highest lakes in the world distributes on the Tibetan Plateau,China.Lake Nam Co,in the North Tibet,is the highest great lake in the world,and is the second biggest salt water lake,only inferior to Lake Qinghai,in China.Biodiversity and community ecology of aquatic plant in this lake will have the impor-tant model and the demonstration significance to other lakes in the Tibetan Plateau. Aquatic plants mainly distributes in the eastern part of Lake Nam Co,and its characters of habitat are diverse,including small puddles,ponds,swamps,streams,as well as connected lakes.The results obtained from the pre-sent field study and literature survey showed that a total of 34 species belonging to 19 genera and 15 families,among which,1 species,1 genera and 1 families belonged to Charophyta,16 species,8 genera and 7 families be-longed to Monocotyledon,and 17 species,10 genera and 7 families belonged to Dicotyledon.Three new recorded families,including Characeae,Callitrichaceae and Scrophulariaceae,three new recorded genera and seven new recorded species were found in Lake Namco and its catchment.The dominant families of aquatic plants in this lake were Cyperaceae,Ranunculaceae,Potamogetonaceae and Haloragaceae.Among all families of aquatic plants,Potamogetonaceae and Cyperaceae included the maximum number of species,accounting for 26.47% and 20.59%,respectively.Potamogetonaceae,Ranunculaceae,Cyperaceae and Zannichelliaceae were most frequently occurring families and the frequently occurring genus included Potamogeton,Batrachium,Zannichellia and Carex.The dominant species in frequency included P.pectinatus,Z.palustris,B.bungei var.flavidum and B.Eradicatum and in biomass is P.pectinatus,Myriophyllum spicatum and B.bungei var.flavidum. According to the basis of community classification,there were eleven types of aquatic plant communities in Lake Nam Co in Lake Nam Co,including Ass P.pectinatus,Ass P.pectinatus + B.bungei var flavidum,Ass P.pectinatus + Z.palustris,Ass P.pectinatus + Chara braunii,Ass P.pectinatus + M.spicatum,Ass L.aquatica + B.Eradicatum,Ass M.spicatum + B.Eradicatum,Ass Limosella aquatica,Ass M.spicatum+ P.pectinatus + B.bungei var flavidum,Ass P.pectinatus + B.Eradicatum and Ass M.spicatum+ P.pectinatus + B.eradicatum.The flora of aquatic vascular plants in the Lake Nam Co was fundamentally north temperate in nature. The interspecific correlation coefficients exhibited by constellation diagram showed the significant associa-tions between the lake shore wetland species in Lake Nam Co,Tibetan,indicating a continuum of the species groups.Quadrats investigation indicated that these types of aquatic plant communities were mainly composed of submersed macrophyte communities with few floating-leaved macrophytes.β-diversity analyses suggested sig-nificant variations in species assembly among different quadrats along the environment gradient. Our research suggested that aquatic plants in the basin of Lake Nam Co possessed a wide range of ecological adaptation and niche separation,and played important roles in the linking of soil and water environment and in the maintenance of species diversity of land and water interface on the Tibetan Plateau.