Little is known about consequences of Spartina alterniflora invasion on soil sulfate-reducing bacteria (SRB). This study compared the abundance, diversity, and community structure of SRB in S. alterniflora and in native plant communities along a successional gradient (bare mudflat, young/mature S. alterniflora, Suaeda salsa, and Phragmites australis) in coastal salt marshes of Eastern China. Quantitative polymerase chain reaction of dissimilatory sulfite reductase (dsrB) gene was applied to assess SRB abundance, and the diversity and composition of SRB was analyzed by 454 pyrosequencing of partial dsrB gene. We found that S. alterniflora had a significantly higher abundance and diversity of SRB than native plant species. For all plant covers, Desulfobacteraceae was the largest soil SRB group, with a relative abundance of 33.6%, followed by Desulfobulbaceae (29.2%). S. alterniflora showed a higher relative abundance of Desulfobacteraceae (42.5%) than native species (29.5%) did. Notably, S. alterniflora invasion decreased the relative abundance of a SRB branch clustering with the thermophilic Thermodesulfovibrio yellowstonii. In conclusion, S. alterniflora invasion of the eastern coast of China has greatly increased the abundance and diversity of SRB communities and altered their structure. This might further influence carbon mineralization and inhibit the production of methane in China's coastal marshes.