We investigated the synergistic succession of the small mammal and herbaceous communities after farmland was reconverted to seasonally flooded wetlands in the Dongting Lake Region of China. The composition of small mammals and the herbaceous community was examined in four habitat types: F (farmland), S (where agriculture continued, but human habitation ceased), R (farmland reconverted back to seasonally flooded wetlands), and B (aboriginal seasonally flooded wetlands). Using various diversity indices, the data showed that the small mammal community changed in parallel with the succession of the herbaceous community. Compared to F, there was little change in S, whereas R noticeably changed. Microtus fortis inhabited R, because Carex spp. was the dominant plant species. R held a mixture dominant species from both F and B, demonstrating that R was in transition (intermediate stages of succession) from F to B. However, the status of the small mammal community in B changed in 2008–2010, due to the operation of the Three-Gorge Reservoir (TGR). In conclusion, our observations demonstrate that the succession of the small mammal community in habitats R and B are directly influenced by human activity in the region, with monitoring being required to continue documenting these changes.