Abstract: Qinghai Lake is the largest inland-plateau saltwater lake in China，which is very important in ecological environment. The landscape of eastern Qinghai Lake is the sandy land，Xiaopohu wetland locates in its east，so study of the interspecific relationships among species on the Xiaopohu wetland is favorable for the vegetation restoration of eastern Qinghai Lake. 53 sample plots of 1 m×1 m were delimited around the Xiaopohu stations，the distance between the two plots is 100 meters，the plots were used to record the quantitative community features: including the species，coverage，height and the elevation，as well as latitude，longitude，circumstance，and geographical features of each sample plot during August 2012. Taking the important values of species over 1 as the dominant species, the related study was carried out. The X2-test，Pearson’s correlation coefficient and Spearman’s correlation coefficient are used to study the interspecific relationships among the 19 main species in Xiaobohu，which is the typical wetland in Qinghai Lake Nature Reserve，and with the help of results of clustering analysis on their relative height，relative frequency，relative coverage and importance value，the ecological species groups were divided. The results are as follows：There are 53 species in the sample plots of study area，the main dominant species are Triglochin maritimum，Blysmus sinocompressus，Kobresia pusilla，et al. Spearman’s correlation analysis is more sensitive to the affinity among species compared with [X2-test] and Pearson’s correlation analysis. Spearman rank correlation analysis showed that the total associations among all the species in Xiaopohu Wetland are unremarkable negatively significant and the unremarkable couples of species account for the highest proportion，significant and extremely significant correlation account for 11.7% in the total number，there are significant positive correlation among the species，such as Carex tristachya and Kobresia pygmaea，Herba Taraxaci and Stellera chamaejasme，Hordeum violaceum and Pleurospermum hookeriva etc. There are significant negative correlation among the species，such as Triglochin maritimum and Blysmus sinocompressus，Triglochin maritimum and Stellera chamaejasme，Triglochin maritimum and Pleurospermum hookeriva etc. The plant communities tend to grow independently. The reason is that plants adaptation to the environment and different resources space. According to the difference of soil moisture and salinity，Xiaopohu wetland can be divided into swamp meadow，swamp beach，wet beach and Kobresia meadow，the different plant species are in different habitats. According to the results of the Spearman’s correlation analysis and cluster analysis，19 main dominant species in Xiaopohu wetland can be divided into three biological groups，the Triglochin maritimum and Blysmus sinocompressus ecological species group，the Kobresia pusilla species group，and Graminifolia species group. Triglochin maritimum and Blysmus sinocompressus ecological species groups are mainly the humidogene and the aquatic plants，caused by adaptation to the swamp meadow and swamp beach，which have high moisture and salinity in soil. As far as Kobresia pusilla species group，the ecotype is primarily characterized by the mesophyte plants and the humidogene plants，they grow in wet beach and Kobresia meadow，where the water and the salinity in soil is moderate. Graminifolia species group is primarily characterized by the mesophyteor and the xerophyte plants，they distribute in the slightly higher terrain platform. Suggestions are as follows: to strengthen the monitoring of Xiaopohu wetland vegetation change in long time，and to ensure the timeliness and effectiveness of protective measures.

Key words: Qinghai Lake, Xiaopohu Wetland, inter-specific correlation, ecological group