Marsh wetlands in northern China play an important role in controlling water resource supply, mitigating soil erosion, and curbing grassland desertification. It is of great significance to clarify the species composition and diversity characteristics of these plant communities to improve their ecosystem service function. However, few studies have been conducted to investigate large-scale wetland vegetation in northern China. Soil moisture is one of the leading environmental factors driving the development of plant communities. In this study, we aimed to understand the characteristics of plant communities and key drivers of seven typical marsh wetlands in northern China. The relationship between the species composition, diversity characteristics and environmental factors, and the distribution characteristics of clonal species of plant communities under low and high soil moisture conditions of these wetlands were compared. The enfluences of environmental factors on community characteristics and distribution characteristics of clonal species were analyzed. The results showed that the species composition and diversity of plant communities among these marsh wetlands were significantly different, but there was no obviously zonal distribution pattern. In these marsh wetlands, the species distribution was regional. The species diversity of the communities was influenced by combination of the environmental factors, such as precipitation, temperature, and soil nutrients. The species composition and diversity of plant communities in marsh wetlands differed significantly between high and low soil moisture conditions. The species diversity indices of plant communities under low soil moisture condition were significantly higher than those under high soil moisture condition. The redundancy analyses of species diversity and environmental factors showed that environmental factors at low soil moisture conditions explained 98.96% of the variation in species diversity, which was mainly influenced by precipitation and total nitrogen, while environmental factors at high soil moisture conditions explained 99.02% of the variation in species diversity, which was mainly influenced by temperature and total phosphorus. The number and coverage of clonal plant species accounted for a high proportion in marsh wetland plants under high soil moisture condition, indicating that clonal species were more adaptable to high soil moisture condition than non-clonal species. The results indicated the regional distribution characteristics of marsh wetland vegetation in northern China and the main influences by precipitation and temperature. With the increase of soil moisture, the diversity of plant communities decreased, but the importance of clonal plants increased. Therefore, future changes in precipitation and temperature may further influence the composition and diversity characteristics of vegetation in the region.