Considering the difficulty in deep dewatering of dredged sediment in Haihe River in Guandu District，we carry out experiments on flocculation concentration combined with plate-and-frame filtration. Specifically，three flocculants，namely，anionic polyacrylamide（APAM，with a molecular weight of 1 500），cationic polyacrylamide（CPAM，with a molecular weight of 800），and non-ionic polyacrylamide（NPAM，with a molecular weight of 900），are used for flocculation concentration. Then，we perform pressure filtration tests on the two kinds of selected concentrated slurry separately by a diaphragm plate-and-frame filter press. Next，we use the KD20 plates to fill the slurry chamber（with a thickness of 200 mm），with continuous feeding of 10 min at the extrusion pressure of 0.8 MPa. Finally，the optimal flocculant is selected according to the plate-and-frame filtration results. The test results reveal that for the dredged sediment with a high organic content，CPAM with a molecular weight of 15 million and a degree of hydrolysis of 14% has a better flocculation effect，and upon concentration，the dewatering effect and effluent quality of the plate-and-frame filtration of slurry are better. The pressure time is 30 min，and the water content of the mud cake can be reduced to below 40%.