Abstract: Thirty plots of herbaceous community were set up in the Shihe river riparian wetland of Xinyang city. The TWINSPAN classification and DCA ordination methods were used to divide community types, while the CCA and RDA ordination methods were used to explore the effects of environmental factors on plant distributions and species diversity. The results showed that 30 plots could be divided into three community types, those were Beckmannia syzigachne + Rumex acetosa + Polygonum orientale, Digitaria sanguinalis + Bidens pilosa + P. hydropiper and Chenopodium album + R. acetosa, while B. syzigachne + R. acetosa + P. orientale was the dominant type. TWINSPAN and DCA clearly reflected the variations of moisture gradient within community habitats. CCA indicated that soil available nitrogen and available potassium were the primary environmental factors that determined plant species distribution, most species trended to distribute in the low and medium levels of soil nutrients. RDA indicated that Patrick richness index had significantly positive relationships with soil pH value, Shannon-wiener and Simpson diversity index all had significantly positive relationships with soil available potassium, while Pielou evenness index had highly negative relationships with soil available nitrogen.