Abstract: The coastal tidal flat of the Pearl River estuary which was leached by distilled water to make the salt contents less than 0.2% was taken as the object of our study. Eight desalination levels were set to analyze the total sulphur, water-soluble sulphur and acid-volatile sulphur in the costal tidal flat during different leaching desalination stages in different depth. The results show that, the concents of the total sulphur decreased in the process of leaching desalination during which the inorganic and organic sulphur decreased 40% and 30%, respectively; the concents of the water-soluble sulphur also went down in this process; the contents of the acid-volatile sulphur were higher than the original contents after leaching, but they reduced gradually among the eight treatments along with the leaching process, owning to the impact of Eh in the soil, according to the Spearman relationship analysis, there was very remarkable negative correlation(r=-0.733～0.933,p<0.01)between the redox potential and the acid-volatile sulphur content within different treatments