Abstract: The soil of Chagan Lake wetland in the saline alkali area of Songnen Plain was used as the research material, and the simulation freeze-thaw culture method was used to study the effects of different freeze-thaw temperatures and freeze-thaw cycles on the changes in soil water-soluble organic carbon（WSOC） content and the fluorescence characteristics of water-soluble substances, in order to reveal the response of water-soluble substances in saline alkali wetland soil to freeze-thaw cycles and freeze-thaw temperatures, provide reference for evaluating soil fertility, rational utilization of resources and remediation of soil environment.The results showed that the soil WSOC content in the 0-20 cm soil layer of the wetland was higher than that in the 20-40 cm soil layer.Freezing and thawing interference had a significant impact on the content of water-soluble organic carbon in soil.As the number of freeze-thaw cycles increased, the content of water-soluble organic carbon in soil showed an increasing trend.The interaction between freeze-thaw temperature and the number of freeze-thaw cycles affected the variation of soil water-soluble carbon content.The soil WSOC of different freeze-thaw treatments was composed of humic acid like substances, with the highest content of humic acid found in samples at-25-5 ℃ freeze-thaw temperatures.The freeze-thaw treatment affected the fluorescence intensity of soil water-soluble substances, but did not affect the structural changes of soil water-soluble substances.