Silicon (Si) is one of the most abundant elements in the Earth’s crust but its role in governing the biogeochemicalcycling of other elements remains poor understood. There is a paucity of information on the role of Si in wetlandplants, and how this may alter wetland C production and storage. Therefore, this study investigated Si distribution,nutrient stoichiometry and lignin abundance in Phragmites australis from a wetland system in China tobetter understand the biogeochemical cycling and C storage. Our data show that Si content (ranging between0.202% to 6.614%) of Phragmites australis is negatively correlated with C concentration (38.150%–47.220%).Furthermore, Si content was negatively antagonistically related to the concentration of lignin-derived phenols inthe stem (66.763–120.670 mg g-1 C) and sheath (65.400–114.118 mg g-1 C), but only a weak relationship wasobserved in the leaf tissue (36.439–55.905 mg g-1 C), which is relevant to the photosynthesis or stabilizationfunction of the plant tissues. These results support the notion that biogenic Si (BSi) can substitute lignin as astructural component, due to their similar eco-physiological functions, reduces costs associated with ligninbiosynthesis. The accumulation of BSi increased total biomass C storage and nutrient accumulation due togreater productivity of Phragmites australis. On the other hand, BSi regulated litter composition and quality (e.g.,nutrient stoichiometry and lignin) that provide a possibility for the factors affecting litter decomposition. Thuscompeting processes (i.e., biomass quantity vs quality) can be influenced by Si cycling in wetlands.