Microbial communities in aquatic sediments are highly sensitive to environmental changes and serve as key indicators for assessing ecosystem health. As an emerging ecological remediation material, calcium peroxide (CaO₂) has showcased increasing application in the treatment of aquatic sediments, and its impact on microbial communities has become a frontier topic in ecological research. This review fucoses on the influencing mechanisms of CaO₂ on microbial communities in aquatic sediments from the perspective of microbial ecology. CaO₂ exerts multidimensional effects on the structures and functions of microbial communities by significantly altering the redox environment of the sediments. Regarding the community diversity, CaO₂ substantially enhances the alpha-diversity and species richness of microbial communities. In terms of the community composition, CaO₂ promotes the proliferation of functional genera such as Nitrosomonas and Thiobacillus, which possess ammonia-oxidizing and sulfur-oxidizing capabilities, respectively, while suppressing the growth of anaerobic fermenters (e.g., Clostridium) and sulfate reducers (e.g., Desulfovibrio). This function-oriented control mechanism indicates that CaO₂ selectively enriches microbial groups that facilitate nitrogen and sulfur cycling, while inhibiting the proliferation of anaerobic taxa that produce harmful metabolites, thereby optimizing the functions and structures of microbial communities in the sediments. This review further elucidates the ecological effects of CaO₂ on microbial communities, revealing its mechanistic role as an ecological remediation material in regulating microbial ecosystems within aquatic sediments. These findings provide significant theoretical references and scientific foundations for ecological restoration of waterbody sediments.