Abstract: The development in mercury biogeochemical cycle in hydroelectric reservoirs both at home and abroad is reviewed in this paper Basically,it contains four aspects,namely,the substrate mercury release behavior,the impact of mercury release on the water column,the transfer and bioaccumulation of mercury in the aquatic food chain and the reservoir's effect on the mercury distribution in the river.On these basis,the development tendency of this research is proposed since there is still some confusion and obscurity.