Abstract: Decomposition experiment of the litter of emergent aquatic plant bulrush was carried out to investigate the influence of the decomposition process on the water quality under different dosage of the bulrush litter. Meanwhile, the effect of sediment addition on the decomposition process was also studied. The results showed that the water quality was greatly changed during the decomposition process of bulrush litter, resulting in the decrease of pH and DO, and the increase of TOC, TN, NH₃-N, NO₃^--N, NO₂^--N and TP at different level. When 0.4 g/L of bulrush litter was added, the lowest value of pH and DO in the water reached 5.13 and 3.11 mg/L respectively which were both lower than the initial values (7.78 and 8.17 mg/L). Moreover, TOC, TN, NH₃-N, NO₃^--N, NO₂^--N and TP reached 28.67, 2.21, 1.43, 0.61, 0.28 and 0.28 mg/L respectively, which were all higher than the initial values (0). Additionally, the change scope of water quality with sediment addition was obviously smaller than that without sediment during the decomposition process. Therefore, the decomposition of bulrush litter should be proceeded with sediment addition.