In traditional research people mainly employed the laboratory simulation experiments to characterize the spatial distribution of interactive interface between salt and freshwater.However,these approaches did not take into account the scale effects and heterogeneity of stratum structure.To address these problems,a typical profile was selected from the piedmont plain to the alluvial coastal plain in the south part of Shandong Province.The water table and samples were collected from this profile within a cycle period of flood-ebb fluctuations,and the multivariate statistical analysis method was used to describe the spatial distribution of this interactive interface.The results indicated that the interactive interface distributed as an inverse U-shape and the burial depth was between 0.3 to 1.5 m vertically with the central point at the depth of 0.9 m at X5 point,and its intrusion intensity variance with depths was 0.9 m > 0.6 m > 1.2 m > 1.5 m.Under the condition of gravity activity the interactive interface migrated deep,showing a tendency of quicker saline-water intrusion and slower desalination.The groundwater type changed as an iterative process from bicarbonate type to chloride type in this interactive interface.