Wetland plants play a vital role in maintaining wetland ecology and ecosystem stability. In order to evaluate the diversity of wetland plants in the Qixing River Basin, two sites, namely, Qixing River Nature Reserve and Sanhuan Pao Nature Reserve, were selected for the study. A total of 194 plots were investigated in 2016 and 2017 using a 1 m quadrat survey, and TWINSPAN was used to classify the plots. The factors affecting biodiversity were analyzed using the generalized linear model. The results showed that there were 532 species of wetland plants, belonging to 80 families and 212 genera, in the Qixing River Basin. The main community types were Carex humida-Carex cryptocarpa association; Glyceria spiculosa association; Nuphar pumilum-Myriophyllum verticillatum association; Carex pseudo-curaica association; Calamagrostis angustifolia-Carex schmidtii association; Glyceria acutiflora-Phragmites australis association; Phragmites australis association; Aldrovanda vesiculosa association, etc. The indices indicated that species diversity of the Glyceria spiculosa association was relatively simple, and that of the Phragmites australis association was high. The results of generalized linear model indicate that species diversity is closely related to vegetation density, and the higher the vegetation density, the lower the species diversity. This study provides important basic data for the study of species diversity in the Qixing River Basin.