Abstract: Bidens frondosa L. is an annual herbaceous plant native to North America. Owing to its high phenotypic plasticity, strong competitive ability, and prolific reproductive capacity, it has become one of the typical invasive alien plants in the wetlands of Beijing. Interactions between alien plants and soil fungi are considered important mechanisms driving successful biological invasions. To investigate the responses of soil fungal communities to different invasion intensities of B. frondosa and identify the key influencing factors, we selected four wetland habitats in Beijing and established four invasion intensities, including non-invaded (coverage=0), lightly invaded (0<coverage≤35%), moderately invaded (35%<coverage≤75%), and heavily invaded (coverage>75%). A total of 96 soil samples were collected. Using high-throughput sequencing combined with analyses of soil physicochemical properties and enzyme activities, we explored the response patterns of soil fungal communities to different invasion intensities of B. frondosa. The results showed that, with increasing invasion intensity, the activities of soil enzymes (acid phosphatase and catalase), as well as key soil nutrient indicators including organic matter and total nitrogen, exhibited an increasing trend. Invasion intensity of B. frondosa did not significantly affect the α-diversity of rhizosphere soil fungal communities, whereas significant differences were observed in β-diversity. After invasion by B. frondosa, the relative abundances of Rozellomycota and Zoopagomycota first decreased and then increased with increasing invasion intensity. Redundancy analysis indicated that the composition and distribution of rhizosphere soil fungal communities were closely associated with soil factors, which together explained 52.97% of the variation in fungal community composition. Correlation analysis indicated that Rozellomycota showed positive correlations with available phosphorus, total nitrogen, and soil moisture, and negative correlations with available potassium, total potassium, nitrate nitrogen, and urease activity. Zoopagomycota was positively associated with available phosphorus, soil organic matter, total nitrogen, ammonium nitrogen, and soil moisture, but negatively associated with pH, available potassium, total potassium, urease activity, catalase activity, and sucrase activity. In summary, the rhizosphere soil environment and fungal community composition of B. frondosa showed significant gradient changes under different invasion intensities, and soil nutrients, soil moisture, and enzyme activities may serve as important environmental factors affecting fungal community structure.