Because of the influence of global change and external disturbances,habitats of alpine meadows are trending toward aridification in the Qinghai-Tibetan Plateau.How would variation in habitat affect the elevational pattern of species diversity?Nine sample plots were set along an elevational gradient in the Dongda Mountains in southeast Tibet.Ten 1m*1msample quadrats were set in each sample plot,with five quadrats located in wet habitat and the others located in dry habitat.Species composition in each quadrat was investigated. Species with a frequency lower than seven were defined as occasional species;otherwise,the species were common.For total occasional and common species,variation ofalpha,beta,andgammadiversity were respectively analyzed along the elevational gradient.betadiversity was measured by the Cody index(betac),multiplicative partitioning (betaw),and the slope of regression between similarity of species composition and distance(beta_(slope)).There were 160 seed plants recorded in these sample plots,among which,132species were distributed in wet habitats and 107 species in dry habitats.For total and occasional species,alphaandgammadiversity both decreased with elevational gain in wet habitats but increased in dry habitats.For common species,alphaandgammadiversity both presented an increasing trend with elevational gain in wet and dry habitats.The elevational patterns ofbetaindexes were not consistent,betacandbetawin wet habitats were higher than that in dry habitats,andbetacandbetawof occasional species was higher than that of common species.The elevational patterns of species diversity between wet and dry habitats were different,and diversity of occasional species had a high value,and will directly affect elevational patterns of species diversity.