The water, pore water, sediment, and fish samples were collected from the Hongfeng Reservoir in November 2003 and February 2004 in accordance with trace metal protocols. The average concentrations of total mercury (THg), dissolved mercury (DHg), reactive mercury, dissolved gaseous mercury, total methylmercury, and dissolved methylmercury in the water columns were 8.00, 5.70, 0.63, 0.05, 0.16, and 0.07 ng/L, respectively. THg and DHg in the water columns, THg in pore water and THg in lake sediments of the Hongfeng Reservoir showed the level of mercury in the Hongfeng Reservoir was higher than in other natural waters in the world due to the loading of a lot of waste water with relatively high concentrations of mercury, whereas methylmercury concentrations in fish (wet weight) varied from 1.73-51.00 ng/g, much lower than in most remote lakes and reservoirs reported in northern Europe and North America. Methylmercury distributions in pore water and sediments showed methylation occurred mainly in the upper several centimeters of sediment cores in the Hongfeng Reservoir. The concentrations of dissolved organic carbon, total suspended particles, total Hg, and methylmercury were higher at Houwu than those at Daba in November 2003. It is suggested that other pollutants such as N and P from fishing farm and other waste water at Houwu,which resulted in deterioration of water quality, affected the concentrations and distributions of mercury species in the reservoir.