In order to explore the influence mechanism of different adsorbents (phosphorus-locking agent and oxygen-enhancing agent) on the endogenous pollutant Co in sediments, the Meiliang Bay of Taihu Lake was selected as the study area. Three groups of indoor simulation experiments, including the control group, oxygen-enhancing group and phosphorus-locking group, were designed in this study. Water samples were collected in four stages (the 4th, 30th, 90th and 150th day after the addition of adsorbents) based on the high-resolution pore water sampling device (HR peeper). The vertical distribution characteristics and interaction mechanism of dissolved Co, Fe(Ⅱ) and Mn in sediment profile under the in-situ coverage were explored. The results show that phosphorus-locking agent and oxygen-enhancing agent did not cause drastic changes in Eh and pH in the water body. The dissolved Co concentration in the sediment profile decreased by 1.29%-45.87% while the adsorption effect was the best at 30th day. Comparing with the control group, the release flux of Co at the sediment-water interface of oxygen-enhancing group and phosphorus-locking group decreased by 1.00.μg/(m2·d) and 1.19 μg/(m2·d), respectively. The release of Co in the sediment profile was controlled by the redox of Fe and Mn, and mainly by the redox of Mn. In addition, the adsorption effect of oxygen-enhancing agent on Co was better than that of phosphorus-locking agent, and the reaction time was also longer.