In this research, the relationship between soil salinity, sodicity, environment factors, and the plant community distribution under micro-topography were analyzed using canonical correspondence analysis method (CCA) in Songnen Plain of China. The experiment was conducted at the Da'an Sodic Land Ecological Experiment Station of the Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences. A representative saline-sodic area measuring 100×100 m was selected within the experimental station for soil sampling. The experimental area was divided into 10×10 m grid squares, and 40 grids were randomly selected as sampling points. The experiment was conducted during 1 May to 1 October for two different hydrological years (year 2005 is a wet year and year 2007 is a dry year). Soil salinity and sodicity parameters included soil ions (Na⁺, K⁺, Ca²⁺, Mg²⁺, CO₃^2-, HCO₃^-, Cl^- and SO₄^2-), soil salinity content (SC), electrical conductivity (EC), sodium adsorption ratio (SAR), and pH. The environmental factors investigated were ground elevation, surface ponding time, surface ponding depth, and soil moistures at four soil layers (0-10, 10-30, 30-60, and 60-100 cm). Experiment results indicated that micro-topography has significant impacts on the spatial variations of soil water, soil salinity, and plant community distribution. Among the eight soil ions, CO₃^2- showed the strongest correlation with the ground elevation. Soil moisture showed negative correlation with the ground elevation. The Suaeda glauca community is the highest salt-tolerant species and is distributed in the mound (highest elevation) of the local micro-topography, where the soil has the highest concentrations of CO₃^2-, Na⁺, Ca²⁺, and Mg²⁺. The Echinochloa crusgalli community and Phragmite Australis community are distributed in the depression of the micro-topography, where the soil has relatively higher soil moisture and lower soil salinity. The Chloris virgata community and Puccinellia tenuiflora community are distributed in the areas between mound and depression. Results of CCA analysis also indicated that under dry condition of year 2007 the plant community succeeded from Echinochloa crusgalli community to Chloris virgata community,and from Chloris virgata community to Suaeda glauca community due to the fact of decrease in soil moisture and increase in soil salt and alkali. However, the plant community distribution (Puccinellia tenuiflora and Phragmite Australis) remained relatively stable under the dry condition. The CCA analysis and variance analysis also identified the threshold values of driving the plant community succession from Echinochloa crusgalli community, Phragmite Australis community to Chloris virgata community and Puccinellia tenuiflora community were Na⁺ (991 mg/kg), CO₃^2-(396 mg/kg), EC (680 μs/cm),and pH (10). Threshold values of driving the plant community succession from Chloris virgata community,Puccinellia tenuiflora community to Suaeda glauca community were revealed by CCA analysis and variance analysis to be: Na⁺(1570 mg/kg), CO₃^2-(576 mg/kg), and EC(879 μs/cm). Ponding time and ponding depth were identified by CCA analysis and variance analysis to be important hydrological characteristic values of distinguishing plant distribution between Echinochloa crusgalli community and Phragmite australis community, and plant distribution between Chloris virgata community and Puccinellia tenuiflora community. Results from this research may serve as the scientific basis for the plant restoration and saline-sodic soil reclamation in Songnen Plain of China, one of the most serious saline-affected areas in the world.