To investigate the influence of microbial communities on arsenic speciation in lake sediments of the Hetao Basin in Inner Mongolia during the ice-bound period, the sediments from Wuliangsuhai（WLSH）were taken as the research object. Using 16SrRNA high-throughput sequencing technology, the structural characteristics of microbial communities in WLSH sediments during the ice-bound period were studied. Additionally, methods such as redundancy analysis（RDA）, correlation analysis, and co-occurrence network analysis were employed to explore the response relationship between sediment microbial communities and arsenic speciation during the ice-bound period. The results indicated that, apart from the residual arsenic, strongly adsorbed arsenic and arsenic co-precipitated with AVS（Acid-extractable sulfides in sediment）, carbonates, manganese oxides, and poorly crystalline Fe hydroxides accounted for a relatively high proportion in the sediments of WLSH during the ice-bound period. When the sedimentary environment was unstable during the ice-bound period, there was a risk of secondary release of arsenic in the sediments of WLSH. The microbial community in the WLSH sediments during the ice-bound period exhibited abundant diversity, and the richness and diversity of microbial community species showed obvious spatial distribution characteristics. There was a significant collinear relationship between microbial communities and arsenic speciation during the ice-bound period, with Thiobacillus, Bacillus, Steroidobacter, Desulfosarcinaceae, and Anaerolinea exhibiting the most pronounced effects on arsenic speciation. Furthermore, adsorbed As, As co-precipitated with AVS, carbonates, manganese oxides, and poorly crystalline Fe hydroxides, as well as As in pyrite, could mutually transform during the ice-bound period, and Thiobacillus and Steroidobacter played crucial roles in this transformation process. This study aims to explore the impact of microbial communities on arsenic speciation in sediments of WLSH during the ice-bound period, providing a microbial theoretical basis and scientific evidence for lake arsenic pollution control. It provides significant implications for the rational development and utilization of water resources, as well as the protection and restoration of aquatic ecological environments.