The authors took soil and water samples, and analyzed the groundwater chemical characteristics and soil salt characteristics in the study area. The results show that the micro-confined water in the coastal plain of Jiangsu is marine sedimentary water, mainly salt water, and the main chemical type is Cl-Na. The salt of micro-confined water mainly comes from sea water. Salt content of suppling period soil is higher, and the soil type is weak saline soil and chlorine saline soil. The salt content in the soil is mainly from seawater immersion, and the Na+ in the groundwater and the exchangeable calcium ions in the formation, magnesium ions produced cation exchange. Main indexes of soil and groundwater salinity show a corresponding linear positive correlation. The linear regression model of salinity with each index of suppling period soluble salt was established and verified by the HYRD1 well . Model effect is good, which illustrates the analysis of soil salinity has instructions in water salinization.