In order to study the functional niche characteristics and main limiting environmental factors of plant communities in different habitats of Baiyangdian wetland. This study takes the floodplain herbaceous plant community and the aquatic plant community in Baiyangdian as the research objects. Functional niche hypervolume was hired to quantified the functional niche under different habitats in Baiyangdian wetland. Sørensen index was used to calculate the overlap degrees of functional niche hypervolumes for plant communities in different habitats. And then, this study explored the key environment factors affecting the functional niche hypervolumes of plant communities in different habitats. The results showed that the functional niche hypervolumes of plant communities in different habitats was significantly different, the functional niche hypervolumes of aquatic plant community were higher than those of floodplain herbaceous plant community. The overlap degree of functional niche hypervolumes was small between plant communities in the two habitats with overlap index 0.32. Alkaline-hydrolyzable nitrogen and total phosphorous were the main environmental factors affecting the functional niche hypervolumes of floodplain herbaceous plant community. The key environmental factors affecting the functional niche hypervolumes of aquatic plant community included alkaline-hydrolyzable nitrogen, available phosphorous and ammonia nitrogen. The functional niche hypervolumes were significantly positively correlated with the content of nitrogen, and negatively correlated with the content of phosphorous of plant communities in the two habitats. In conclusion, the plant communities showed obvious functional niche differentiation in different habitats, and the convergence degree of functional niche space of floodplain herbaceous plant community was higher than