Abstract: As a gateway for pollutants to enter plant tissues, the iron plaque (IP) on root surface plays an important role in the phytoremediation of heavy metal contaminated sediment. The anoxic condition in the sediment caused by the degradation of organic matters significantly effects the formation of IP on root surface and change the biogeochemical processes of heavy metals, thereby affecting the phytoremediation of the heavy metal contaminated sediment. In order to explore the formation of IP on the root surface of emergent aquatic plants and its effect on the accumulation and translocation of heavy metals in anoxic sediment, sucrose was added into sediment to simulate sediment anoxia, and the biomass, IP content on root surface and metal content in the tissues of Canna indica were determined. The results indicated that: (1) The accumulation of metals in plant tissues decreased with the anoxic condition in the sediment. (2) The anoxic condition promoted the formation of IP on root surface and enrichment of Cr and Ni in IP. Under severe anoxic condition, the highest IP content was (10.40±0.30) g/kg of dry root, but the content of Cd, Pb and Zn in IP was reduced. (3) The anoxic condition inhibited the translocation of Ni from the IP to plant tissues, while slight anoxic condition promoted the translocation of Cr and Zn. The effect of anoxic condition on the translocation of Cd, Pb and Cu was not significant. The study shows that the anoxic condition in sediment promotes the formation of IP on root surface of emergent macrophytes and affects the accumulation and translocation of heavy metals via IP with different patterns depending on the anoxic levels and the metal species.