Aquatic vegetation's important structuring function in shallow freshwater ecosystems has been increasingly recognized as an important ecological restoration measure to rehabilitate heavily polluted water. Nitrogen (N) is one of the most important limiting elements in aquatic ecosystems, and the growth of rooted aquatic macrophytes profoundly affected sediment N biogeochemistry. Due to variable requirements of N for the different growth phases of Phragmites australis, as well as metabolism extensity of macrophytes is changing, it is thereby unclear how the holistic growth period of aquatic macrophytes affects sediment N cycling in eutrophic lakes. In this study, combined intact sediment core microcosm batch experiment and flume modelling, a 120-d simulation study was conducted to investigated changes of total nitrogen (TN), inorganic nitrogen and total exchangeable form of nitrogen (TF-N) in sediments surrounding rhizosphere of P. australis during the whole growth of P. australis. The results showed a priming effect of sediment N by P. australis was observed, with the contents of total inorganic nitrogen (TIN) and TF-N in sediments gradually increasing, while TN and non-exchangeable form of nitrogen (NTF-N) declining. During the experiment, the exponential-increasing biomass of P. australis remarkably promoted the contents of ammonium nitrogen (NH⁺₄-N) and nitrate nitrogen (NO^-₃-N), but not for nitrite nitrogen (NO^-₂-N). Compared with the initial values of TF-N, on day 120, the contents of the exchangeable form (IEF-N), carbonate form (CF-N), iron-manganese oxides form (IMOF-N) and organic matter-sulfide form (OSF-N) in surface sediments increased by 1.10, 3.40, 3.60 and 1.40 times. This phenomenon could be attributed to the root metabolisms-driven redox condition and pH changes in rhizospheric microsites. On day 120, the contents of NH⁺₄-N and NO^-₃-N in sediments dramatically increased, of which were 9.43 and 2.22 times in comparison with those on day 90, suggesting that massive TIN was released into the sediments caused by senescent processes of litter from P. australis. In brief, to improve the restoration efficiency and long-term stabilization of pollution control, it is of more significance to adopt comprehensive lake physico-ecological engineering measures to manage the litters derived from P. australis.