Abstract: The soil water-salt attributes as well as its dynamics a direct influence on species composition of plant communities in arid region. According to the measurement of the soil water-salt dynamic(soil salt content up to 1m depth, water table and the mineralization degree) and the grassland investigation, a index for characterise the water and salt grades were proposed, and the relationships of the water-salt-plant system in different grassland types were discussed. The natural grassland types near the Grassland Ecology Research Station, Hutubi, Xinjiang, were divided into five forms: marshy lowland meadow, saline lowland meadow, heavy saline lowland meadow, salt desert and heavy salt desert.