Response of litter decomposition and carbon dioxide (CO_2) releases to salinity and inundation has an important significance under the background of global climate warming and saltwater intrusion. This study used a microcosm experiment to determine the impact of different salinity and inundation on litter decomposition and CO_2 releases of Cyperus malaccensis from the Min River estuary,SE China. The results show that,①the litter mass loss rates of in the high salinity (15 pus),middle salinity (10 psu) and low salinity (5 psu) treatments decreased about 10.83%,17.93% and 29.39% compared with control treatment (0 psu) under the flooded condition,and about 24.18%,31.62% and 47.46% under the un-flooded condition, respectively; ② the decomposition rates of C. Malaccensis in the flooded condition of the control treatment was 0.0070 d~(-1)(t_(0.95) = 0.76 a),which was significantly higher than that in the un-flooded condition of 0.0051 d~(-1)(t_(0.95) = 0.94 a) (p<0.05). However,the decomposition rates of C. Malaccensis and its CO_2 release rates were higher in un-flooded condition than in flooded condition for all treatments. Overall,the CO_2 releases rate of C. Malaccensis litter in un-flooded condition increased by 7.05% ~ 86.23% as compared with in flooded condition. ③ During the decomposition period of 95% dry matter, compared with flooded condition,CO_2 releases in un-flooded were higher about 34.49% in control treatment,but inhibited by an increase of salinity. ④ Salinity and inundation contributed about 24.82% and 14.29% to litter mass loss,respectively,and about 75.62% and 6.13% to CO_2 release rates.