Abstract <p><i>Spartina alterniflora</i> is an invasive plant widely distributed in coastal areas of China, and the invasion has caused the accumulation of soil sulfur contents, while sulfide can accumulate to phytotoxic levels. It has been verified that <i>S. alterniflora</i> is more tolerant to sulfide than <i>Scirpus mariqueter</i>. Therefore, sulfide may be may play a significant role in <i>S. alterniflora</i> invasion, but the specific mechanism by which <i>S. alterniflora</i> tolerates sulfides in soil during the invasion process awaits further investigation. Through experiments with situ rhizoboxes in the Jiuduansha Wetland, we conducted field investigations to analyze soil sulfur (sulfate and sulfide) content, iron (Fe(II) and Fe(III)) content, and physicochemical properties. Meanwhile, the effect of roots on soil bacterial communities and sulfur cycle-related microorganisms was investigated. The soil sulfide content in <i>S. alterniflora</i> was 2.4 times higher, and sulfate content was 1.7 times higher than those in <i>S. mariqueter</i>. In the rhizoboxes of <i>S. alterniflora</i>, the contents of soil sulfide in the rhizosphere soil were significantly lower than that in bulk soil. The iron contents in the rhizosphere of <i>S. alterniflora</i> were 6 times higher than that in <i>S. mariqueter</i>. In conclusion, the <i>S. alterniflora</i> may gain an advantage in the invasion process by oxidizing the sulfide through radial oxygen loss and by enriching iron to mitigate high sulfide concentrations in the rhizosphere.</p> Graphical abstract <p></p>