In order to study the extent of CH₄ release at the sediment-water interface (SWI) of the tributary bay of the Three Gorges Reservoir (TGR), CH₄ production and oxidation at the SWI and its regulators in the Xiangxi Bay were investigated by combining in situ sampling and indoor incubation with sediment characteristics and environmental factors. The results showed that: (1) During the discharge period of the TGR, the potential sediment CH₄ production rate (MPs) (6.35-2029.37 mg/(kg·d)), CH₄ production fluxes (MP, 0.04-0.73 mmol/(m²·d)) and oxidation fluxes (MO, 0.03-0.62 mmol/(m²·d)) at the SWI showed spatial variations among several transections and increased from downstream (XX00) to upstream (XX07). (2) Vertically, the CH₄ production rate decreased with increasing sediment depth, and MPs from the top 20 cm of sediment can be used to estimate sediment MPs in the bay, which accounted for 70% (55%-82%) of the total CH₄ production from the intact sediment core (between 20 cm and 36 cm in length). (3) MP at the SWI was positively and linearly related to sediment total organic carbon, but negatively related to water depth. MP and MO showed a very significant positive correlation with increasing temperature, resulting in higher CH₄ emission corresponding to a linear decrease in methane oxidation rate (MR). Accordingly, the sediment MR in Xiangxi Bay reached 96.62% during the discharge period of the TGR, indicating low CH₄ emission from sediments.