Abstract: Two stations of suspended sediments during neap and spring tides were measured in the west channel of the Yalu River. Together with analysis results of surface sediment characters and current forces, this article does some researches about suspended sediment concentration variations and their relations with tides and current forces during spring and neap tides, does calculation of sediment discharge of unit width and net sediment discharges and direction analysis,and gives relations between suspended sediment grain sizes and tides and bed sediments, which mainly involves sediment concentration,discharge and grain size. The results show that the main factors influencing suspended sediment characters are space position,current strength and sediment source. Station 1# is rich in fine sediment, and current and sediment transport are controlled by terrain features. Station 2# has flat terrain and coarse sediment, and sediment source comes from other positions. Suspended sediment concentration varies regularly because of influence of current and tide force,and sediment discharge is dominated not only by current force, but also by sediment source. Suspended sediment grade percentage at two observation poins has different peak values with ebbs and flows resulting from different current velocities,directions and tidal levels. This indicates sediment space distributions and reflects external environment's effects on suspended sediment.