Karst wetlands play a crucial role in heavy metal transport and biogeochemical cycles. This study analyzed heavy metal contents and morphological distribution in sediment samples from Caohai wetlands, Guizhou Province, and investigated bacterial community composition and its interaction with heavy metals using 16S rRNA sequencing. Results showed severe heavy metal pollution in Caohai wetlands, with high bacterial diversity. Bacterial community structure significantly correlated with heavy metal content. The microbial covariance network demonstrated more coexistence than exclusion among bacterial taxa. This study revealed heavy metal pollution characteristics in Caohai wetland sediments and provided a theoretical basis for ecological risk assessment and microbial remediation of heavy metal contamination in karst wetlands.