Abstract: High efficiency of grab dredging equipment and less sediment pollutant release is the key problem of enviormental protection dredging． Based on the requirment of enviormental protection dredging and the specific situation of the invariable backwater zone of the Three Gorges reservoir area，the optional parameters from reducing disturbance and preventing the sediment suspension should be sought to solve the problem of reservoir sedimentation and the second pollution． The author simulate sediment dredging in the invariable backwater zone of the three gorges reservoir area through the traditional grab gredging equipment parameters control such as grab bucket opening，floating bucket angle，frequency of grabing mud． This method could find the optimal parameter combination of minimum sediment pollutant release． The experiment provided the optimal parameter support for the sediment dredging in the Three Gorges reservoir area，combined with the actual requirement of navigation．