Abstract: The effect of Margarya melanioides (M. melanioides) bioturbation on the physical and chemical properties, nutrient content and microbes of the sediment of Ottelia acuminate constructed wetland was investigated through the simulation device of constructed wetland with two kinds of hydraulic retention time (HRT, 7 and 42 d). The results showed that M. melanioides bioturbation on the sediment was strengthen in the depth of 0-3 cm. M. melanioides significantly reduced the pH of the sediment in the depth 0-3 cm under both HRT 7 d and HRT 42 d situation, while increasing the oxidation-reduction potential (ORP) in the depth 0-7 cm significantly. Under HRT 7 d, the content of organic matter in the depth of 0-1 cm of sediment with M. melanioides-added group was significantly lower than that in the control group, which was 8.7% lower. Under HRT 7 d and HRT 42 d, the TN and TP content of the test group sediment in the depth 0-1 cm were both significantly lower than the control group, where TN decreased by 11.0%, 3.9%, TP decreased by 5.8%, 3.2%, respectively. The amount of bacteria of the test group under HRT of 7 d and 42 d was increased by 32 times and 5 times respectively compared with the control group, while the amount of actinomycetes was increased by 7 times and 1 times, respectively. The addition of M. melanioides to the Ottelia acuminate constructed wetland might change the pH and ORP in the surface of sediment, improve the quantity of microorganisms, and play a positive role in the degradation of nutrients in surface sediment. In addition, increased HRT is beneficial to increase the redox conditions of the Ottelia acuminate constructed wetland and decrease the TP content in the sediment.