In order to explore the changes of species diversity of wetland plants in northern water-scarce areas, the Yanqing Guishui River in Beijing was selected as the study area, using species richness (R), Shannon-Wiener Index (H), Simpson Index (D) and Peilou evenness Index (J) as indicators for measuring plant community diversity, the response relationship between plant species distribution and environmental factors in different river sections and regions was studied using the variance method and typical correspondence analysis (CCA). The results showed that there are 93 species of wetland plants belonging to genus 76 and family 44 in the study area, and the dominant families are Asteracea, Poaceae, Fabaceae and Cyperaceae. For these 93 species of plants, the H was less than 3, D and J were between 0.5 and 0.75. The total number of species is not high; however, the distribution is relatively uniform and at a medium level. The major water quality factors affecting the formation and growth of wetland plant communities were Total Nitrogen (TN), pH and Chemical Oxygen Gemand (COD).