Through field investigation, sampling and laboratory analysis, morphological characteristics of the profiles of saline-sodic soils under different land use patterns in the Songnen Plain and variations of content and composition of the soluble salts therein were studied. Results show that under different land use patterns, the soil profiles differed sharply in thickness of humus horizon and organic matter content in the plow layer and the humus horizon. In the four profiles under fenced grassland, upland field, 3-year-old paddy field and 20-year-old paddy field, separately, total content of soil soluble salts, pH and ESP were all higher in the middle layers than in the upper and lower layers. The soluble salts were mostly composed of K⁺+Na⁺, HCO₃^- and CO₃^2-, which indicate that all the four land use patterns tend to inhibit surface accumulation of sodic salt in the top layer. In grazing grassland, the total content of soil soluble salts increased with the decreasing soil depth in the profiles, showing a significant phenomenon of salt surface accumulation. In the profile under 20-year-old paddy field, the soluble salt content, pH and ESP decreased to 0.21%, 7.56% and 9.1% respectively, which suggests that in alkali- saline land growing paddy rice is more contributive to soil desalinization and solodization than managing the land as grassland and upland field.