Abstract: The main driving factor of soil salinization in the arid is seasonal freezing and thawing but the coupling relationship of freezing and thawing in soil water，salt and heat regulation mechanism are still unclear. In this paper the typical saline soil was selected，and collected the data from Manas River Basin，Xinjiang，China，to analyze the dynamic changes of water，salt and temperature at 160 cm soil profile from November 2009 to May 2010，further to investigate the hydrothermal and salt coupling effect between the different soil layers in freezing and thawing processes. Results showed as follows：the most soil freezing depth is 150 cm and its temperature is closely related to the temperature of the surface soil （0-40 cm）; moisture contents showed the "C" distribution pattern，the topsoil and subsoil （100-160 cm） have a high moisture and the inner soil layer’s （40-100 cm） have water contents less than 10%，in the freeze-thaw period，there was an average soil water content increased up to 12.91% and the beginning of the steamed period decreased to 10.01%. While the salinity was significantly gathered at the surface of the soil profile in the freezing period and beginning of steaming period，the inner soil and subsoil salt contents were stable，the whole process for soil salt contents appeared as salt accumulation - desalination - salt accumulation in the process of changes. The study found through hydrothermal and salt analysis that the heat transfer is a key factor in regulating water and salt transport with high degree of energy between the salt and water，furthermore，salt and water performance in the inner soil and subsoil goes side by side and the surface soil water removes by leaving the salt on it. In connection with the mechanism for seasonal water and salt transport in the study area，the research found a comprehensive set of methods to deal with the problems which caused by seasonal freezing and thawing of soil salinization.

Key words: freeze thawing, water and salt movement, salt enrichment, regulatory mechanism, Manas River watersheda