Abstract: In the present study, the effects of mercury release control by sediment capping were investigated to solve the serious mercury pollution problem in the sediments of Lake Baihua in Guizhou province. The inhibition effect on the release of mercury of three different materials of zeolite, hematite and kaoline were studied after being capped onto sediments. Laboratory-scale simulation experiments showed the optimal capping thickness of 2.0 cm for mercury release control, and kaoline was the optimal material, since the inhibition rates were determined to be 47.1%, 64.9% and 62.3% for zeolite, hematite and kaoline, respectively. Water disturbance showed little effect (<6.7%) on sediment capping, as indicated from the slight variation in mercury concentrations in overlying water during the first 7 days after the sediment was capped with kaoline. Moreover, 22,0 m² area in Baihua reservoir, which was severely contaminated with mercury, was isolated with tarpaulins for pilot-scale investigation. Powdered kaoline was carefully spread three times by barges to achieve the capping thickness of 2.0-3.0 cm, and after being settled and stabilized, mercury concentrations in the overlying water and pore water were monitored once a month over the next 6 months. The pilot-scale results demonstrated the significant inhibition efficiency of kaoline capping on the control of mercury release from sediments with a flux decrease ratio as high as 47.1%. The results showed that the mercury release could be effectively inhibited by the capping of kaoline, and 2 cm thickness of the kaoline capping could reduce the engineering cost as well as the ecological impact.