Abstract: To protect the ecological environment and aquatic plant resources in Jiuzhaigou where is famous for its beautiful water scape and virgin forest, it is very important for us to study on the aquatic plant community diversity and the relationship between the βdiversity change and environment gradients.On the foundation of general quadrats investigation and study, this paper applied the Wilson Shmida Index (βT-(to calculate the binary data-and Bray Curtis Index ( CN-(to calculate the numerical data-to measure the βdiversity of aquatic plant community in Jiuzhaigou.In this paper, we respectively used the species number, relative coverage and important value as the numerical data to calculate CN.The primary statistic results showed that there are 75 species (including 23 families, 41 genera-of aquatic vascular plant and 11 types of aquatic plant communities in Jiuzhaigou.The difference of species composition variety as the altitude alters and other factors happens obviously, and the measurement of CN3 whose CN based on important value had better characteristics of synthesis and stability than others.Through analyzing the altitude alters on βdiversity, we found that altitude gradients are the main factors to affect the βdiversity of aquatic plant community.Along with the altitude rise, the change trend of βdiversity index between the first quadrat and each of others come to be one valley (βT-or one peak ( CN), and the two adjacent quadratspcome to be two valleys (βT-or two peaks ( CN).At the same time, the spatial cluster can be spplied on analyzing the βdiversity variety and its effect factors.Spatial cluster analysis results made it chear that the numerical data of βdiversity ( CN3-can be divided into 4 types.Type Ⅰ, Ⅱand Ⅳall belong to the sensitive clusters whose comparability of communities descends when the altitude height rises, and this conclusion showed the altitude gradientps dominant effect to the βdiversity variety.On the other hand, Type Ⅲwhich resulted fromthe factors of non-altitude gradient revealed that the valley character and community type partial effects to the variety of βdiversity.