Abstract: We studied nutrients and biomass of plants in foraging areas of Black-necked Cranes (Grus nigricollis) at Caohai. Our results showed that the Scirpus yagara was the most valuable food plant for Black-necked Cranes for its high content of crude protein, N, P and low content of crude fiber. S. yagara, S. validus, S. triangulates and Heleocharis valleculosa grow in the shallow water area which is accessible to Black-necked Cranes, while Zizania latifolia and Eleocharis vallcculosa live in the deep water that cannot be used by the cranes. Plants with biomass in stems and leaves from high to low are: Typha orientalis> S. yagara>Zizania latifolia> Juncus effusus>S. validus>S. triangulatus>Eleocharis vallcculosa. Our study is critical in guiding management and restoration measures for habitats of Black-necked Cranes at Caohai.