Abstract: Soaking plants decomposed in the Water-level Fluctuation Zone（WLFZ）of the Three Gorges Reservoir (TGR), while nutrients released into the overlying water. Then, greenhouse gases (GHGs) including carbon dioxide (CO₂), methane (CH ₄) and nitrous oxide (N₂O) were formed and emitted. The WLFZ may be an important GHGs source to the atmosphere. In this study, typical herbaceous plants were collected from WLFZ, while plant soaking experiments were conducted with detritus of leaves and stems of Cynodon dactylon (Linn.) Pers.，Polygonum hydropiper，Bidens bipinnata Linn.，Xanthium sibiricum Patrin ex Widder. under indoor incubation conditions. Indexes were determined including the dry weight losses in detritus, physicochemical properties, nutrient concentrations of overlying water and GHGs emission rate of water-gas interface GHGs, in order to investigate the GHGs emission processes, fluxes and interspecific differences of soaking plant detritus. Results showed that: (1) after the plants were inundated, the dry weight was declined rapidly in the first 7 days. The dry weight loss of Xanthium sibiricum Patrin ex Widder. was the highest, while Cynodon dactylon (Linn.) Pers. was the lowest. The pH and DO of the overlying water were reduced at the early stage and increased rapidly in the middle and late stages. The Eh and EC value increased in early days, and decreased later. (2) At the initial stage of plants detritus inundation, GHGs emission from the plant-water-gas interface were rapid, reaching the peak on the 4th to 7th day of inundation, then get stable in the middle and late stages. The release rate of GHGs from Bidens bipinnata Linn. and Xanthium sibiricum Patr ex Widder. were higher than that of Cynodon dactylon (Linn.) Pers. and Polygonum hydropiper. There was a significant positive correlation between CO₂, CH₄ emission rates and DOC concentrations in the overlying water (P<0.01), which was mainly due to the large amount of DOC released by plant soaking. The positive correlation between the N₂O emission rate and the NO^-₃-N concentration of the overlying water was significant (P<0.01), which was mainly due to NO^-₃-N released from inundated plant detritus. The initial carbon and nitrogen contents and plant types may affect plant soaking decomposition rate, leading to different pattens of nutrient release and GHGs emissions. (3) Cumulative emissions of CO₂ and CH₄ from the inundated  Bidens bipinnata Linn.’s and Xanthium sibiricum Patrin ex Widder.’s were significantly higher than those from Cynodon dactylon (Linn.) Pers. and Polygonum hydropiper. The cumulative emissions of N₂O from Xanthium sibiricum Patrin ex Widder., Bidens bipinnata Linn. and Polygonum hydropiper were significantly higher than that of Cynodon dactylon (Linn.) Pers. As a whole, the amount of GHGs emission of Cynodon dactylon (Linn.) Pers. was the lowest under inundation. So, Cynodon dactylon (Linn.) Pers. may be recommended as ecological restoration species in the WLFZ of TGR.