Releasing rate of mercury from the sediments in Jilin-Fuyu reach of the Songhua River is studied through simulating experiments.Releasing rate of mercury is mainly affected by the content and species of murcury in sediments,as well as the content of dissolved oxygen in waters and temperature.Under normal oxygen condition,releasing rate of mercury is linear with the concentration of unstable mercury,and exponential with temperature.The empiric formula about releasing rate of mercury is established.Annual releasing amount of mercury from sediments is estimated.