The interfacial chemical behavior, lattice exchange and dissolution, of FeS(s) as one of the important sulfide minerals was studied. Emphases were made on the surface characterization of hydrous FeS(s), the lattice exchange of Cu(Ⅱ) and FeS(s), and its effect on the dissolution of FeS(s), and also affect some organic ligands on that of both Cu(Ⅱ) and FeS(s), Cu(Ⅱ) which has lower sulfide solubility in water than FeS(s) undergoes the lattice exchange reaction when Cu(Ⅱ) ion contacts FeS(s) in the aqueous phase. For heavy metals which have higher sulfide solubilities in water than FeS(s), these metal ions were adsorbed on the surface of FeS(s) Such a reaction was interpreted by the solid solution formation theory. Phthalic acid(a weak chelate agent) and EDTA(a strong chelate agent) were used to demonstrate the effect of organic ligands on the lattice exchange reaction between Cu(Ⅱ) and FeS(s). The pHzpc of FeS(s) is 7 and the effect of ionic strength is not showed. It can be expected that phthalic acid has little effect on the lattice exchange reaction between Cu(Ⅱ) and FeS(s), whereas EDTA has very decreased the removal of Cu(Ⅱ) and FeS(s). This study shows that stability of sulfide sediments was predicted by its solubility. The pH control of the alkaline-neutralization process to treat heavy metal in wastewater treatment process did not needed. Thereby, it was regarded as an optimal process which could apply to examine a long term stability of marshland closely in the treatment of heavy metal in wastewater released from a disused mine.