Water level affects greenhouse gas fluxes in wetlands. A static chamber-gas chromatographic technique was used to study the release of three greenhouse gases, CO₂, CH₄, and N₂O at simulated water levels (0, 5, 10, and 20 cm) of reed wetlands in the Hangzhou Bay area. The results indicated that, 1) the CO₂ flux was higher at night and lower during the day-acting as sink during daytime and source at night-with a net flux as sink of CO₂ irrespective of water level. CH₄ was lower at night and higher during the day with a net flux as source of CO₂. N₂O flux was lower at night but higher during the day, except at 0 cm; 2) the CH₄ flux and the CO₂ flux increased, followed by a decrease, with increasing water level. The water levels for the highest average fluxes were 10 cm for CH₄ and 5 cm for CO₂; and 3) correlation and principal component analysis showed that water temperature was the dominant factor for the daily variation in soil CH₄ and N₂O flux, and soil temperature was the dominant factor for the daily variation in CO₂ flux. Meanwhile, soil pH, soil Eh, water pH, and water Eh were all important factors for the variation in CO₂ flux.