By in-situ observation and analysis in laboratory, structure and salt-accumulation mechanism infrozen-thawing season in micro scale (a 32 m long transect) of sodic saline soil region were discussed.Results show that texture along soil profile on micro plat was silty sub slay-slay-silt-gravel structure; themain component in micro basin was silt and gravel, lacking of slay layer. Moisture in saline meadow soilsurface layer was mainly in the form of capillary water, porosity of macro capillary can exceed 70% of totalporosity; moisture in sodic alkaline soil was mainly in the form of confined water, the water content was lowand variation range was very weak. The water and salinity transportation in frozen-thawing period werecontrolled by mosaic structure composed by alkaline soil and saline meadow soil. The surface layer of salinemeadow soil became accumulation sink groundwater in frozen-thawing season, in which the water contentcould reach up to 50%; the vast salinity accumulated in surface layer resulted in the saline degree graduallyaggravated in thawing season.