Carbon monoxide (CO) is an important trace reducing gas that can be utilized by marine microorganisms as an energy source. In this study, we combined geochemical analysis and sediment cultivation experiments to explore the in situ distribution characteristics, microbial metabolic pathways, and influencing factors of CO in the coastal wetland sediments of the Yellow River Delta and Jiaozhou Bay. The concentration range of CO in sediments was 58.5~540.3 nmol·L^-1, controlled by processes such as organic matter degradation and sulfate reduction. In the cultivation experiments, CO was rapidly utilized by microorganisms such as sulfate-reducing bacteria, but nitrate had a certain inhibitory effect on anaerobic consumption of CO. In addition, the microbial metabolic rates of CO were affected by environmental factors such as temperature, water content, and salinity. The results of this study enrich the understanding of the biogeochemical cycling of CO in marine sediments.