The distribution characteristics of Cation exchange capacity (CEC) in saucer-shaped depressions to island forests of Sanjiang Plain and its relationship with hydrology and geomorphology, soil nutrients and community characteristics were studied through field sampling and indoor measurement analysis.The results showed that the CEC of soil in the saucer- shaped depressions to island forests of Sanjiang Plain was 9.83 ~ 37.97cmol?kg-1.In the direction of disc-Island forest, the average CEC of the 0-40cm depth soil first increased, then decreased, and then slightly increased, presenting an N shape. The cationic exchange capacity of the soil in the area of Carex lasiocarpa community was the largest (26.82cmol?kg-1), while the smallest was Carex meyeriana community (23.26cmol?kg-1).In the vertical direction, with the increase of soil depth, soil CEC gradually decreases and is in low and moderate variation.The soil CEC distribution in saucer- shaped depressions to island forests is mainly affected by the accumulation of soil organic matter, and the soil total phosphorus and total nitrogen content has an extremely significant positive correlation with the soil CEC content.Soil CEC in saucer- shaped depressions to island forests was significantly negatively correlated with soil potassium content, indicating the weakening effect of potassium on soil CEC in wetland.