<p>The relationship between biodiversity and ecosystem stability is a central theme discussed in the conservation and restoration of wetlands. While numerous studies have established a positive correlation between biodiversity and ecosystem functional stability, the connection between biodiversity and structural stability remains poorly understood. To enhance understanding of the relationship between biodiversity and community structural stability in a sedge mire, while addressing critical knowledge gaps in species diversity-community structural stability linkages. A field survey was conducted to collect plant community data from tussock areas and hollow areas (i.e., areas without tussocks) in the Zoige Plateau. Then we calculated Godron’s stability index to assess the structural stability of plant community and analyzed its relationships with community characteristics. We found that plant species richness and Pielou’s evenness were significantly higher in tussock areas compared to hollow areas (<i>p</i> &lt; 0.05). However, the number of groups was greater in hollow areas. The community structural stability in tussock areas was significantly lower than in hollow areas (<i>p</i> &lt; 0.05). In tussock areas, community structural stability didn’t correlate with species richness (<i>p</i> &gt; 0.05), but it positively correlated with species richness in hollow areas (<i>p</i> &lt; 0.05). Pielou’s evenness negatively correlated with community structural stability in both areas (<i>p</i> &lt; 0.05). A quadratic relationship was observed between the coverage of dominant species and community structural stability in both areas (<i>p</i> &lt; 0.05). Our findings indicate that species composition is likely a more reliable predictor of structural stability in plant communities than species richness.</p>