[Objective] The adaptability and landscape application effects of rainwater garden plants were studied using a multi-index from a biodiversity perspective in order to provide a scientific reference for the optimal allocation of rainwater garden plant communities in Beijing City. [Methods] A field investigation was conducted to analyze and understand the diversity characteristics of rain garden plant communities. Quantitative analysis was used to construct a landscape evaluation model of rain garden plant communities to classify and evaluate 15 typical rain garden plant communities. [Results] ① There were 45 species of rain garden plants belonging to 43 genera and 20 families in Beijing sponge city pilot area. The dominant plant families were mainly Compositae, Gramineae, Liliaceae, Crassulaceae, etc. There was little difference in the index values of different plots in the pilot area, the richness of herbaceous plants was similar, and the concentration of plant species was consistent in the investigated plots. ② The comprehensive evaluation of the rain garden plant community landscape in the pilot area was at a high level, and the evaluation of the rain garden plant community landscape was significantly higher than that of road rain garden plant community landscape. Due to the influence of the pollution in surface runoff in the region causing differences in plant growth, the plant community structure was different at different sites. [Conclusion] In the future, it will be necessary to strengthen regular monitoring and evaluation of constructed rain garden plant communities, screen out dominant species, and summarize the stable plant community allocation patterns and maintenance management methods in order to provide a reference for the selection and configuration of rain garden plants in Beijing City.