Abstract: To reveal the distribution patterns of wetland plant communities across elevational gradients, a combined approach utilizing sampling lines and plots was employed to investigate the plant communities along these gradients in the Shengjin Lake marshland at different seasons. The results showed that the flora of the Shengjin Lake marshland comprised a total of 26 herbaceous plant species, belonging to 15 families and 24 genera, Asteraceae and Poaceae were the dominant families, with Carex thunbergia as the dominant species. Annual and biennial plants accounted for a relatively high proportion of 69.2%. The community structure in the high and middle elevations exhibited similarities, with a notable difference from the low elevation area. Carex thunbergii was the dominant species in all three elevations during both seasons. However, the main associated species differed significantly among the elevations, and there were also some differences across different seasons. Plant species gradually changed from species adapted to long-term flooding to species adapted to short-term flooding, there were few common species among the three areas, with only 4 common species in February and 2 in April. From February to April, the increased flooding in the low elevation area posed greater challenges for plant survival. Additionally, the heterogeneity of the intertidal environment intensified, resulting in the number of common species in the low and middle elevation areas, from 10 to 6. For species diversity, as the elevation gradient increased, the total species count in each area exhibited a general decreasing trend. Specifically, in February, there was a significant difference (p<0.01) in the average number of species between the low elevation area and the other two areas. Due to environmental heterogeneity, the other diversity indices did not consistently reflect a trend corresponding to changes in species richness. From February to April, the average number of species and Shannon index in the low elevation area sample plots decreased significantly (p<0.05), whereas the changes in the high elevation area were not significant. Based on the results, the factors influencing the characteristics of plant communities were analyzed and discussed, with water level fluctuations identified as the primary factor affecting the distribution heterogeneity and diversity of plant communities in the Shengjin Lake marshland.