Abstract: Nitrogen is an important factor influencing eutrophication in lakes, and the dynamics of sediment-associated nitrogen contents can significantly affect water security and aquatic ecosystem health. The Baiyangdian Lake is the largest shallow macrophyte-dominated lake in the North China Plain, playing important roles in supplying water, storing floods and regulating regional climate. The ecological and environmental status of this lake has been given more concerns since Baiyngdian Lake serves as the important ecological barrier of Xiong’an New Area. However, Baiyangdian Lake was facing the eutrophication under the effects of anthropogenic activities and global climate change, and thus some water environment control and ecological water supplying projects have been implemented to protect water quality. Nevertheless, little information is available on nitrogen dynamics in sediments of this lake after these projects. To investigate the spatiotemporal dynamics of nitrogen in sediments and their influencing factors in Baiyangdian Lake, spatial distribution patterns of various forms of nitrogen throughout the entire lake and seasonal variation characteristics in typical vegetation zones (i.e., emergent and submerged plant communities) in typical sub-lakes were investigated and the key factors were identified. The results showed that, on the whole-lake scale, the mean total nitrogen content in sediments reached 3.17 mg/g, with organic nitrogen constituting the dominant nitrogen form. Notably, all nitrogen forms exhibited substantial spatial variabilities except for nitrate nitrogen. On the sub-lake scale, the maximal TN concentration in emergent vegetation areas were observed in summer, whereas submerged vegetation areas showed no significant seasonal variations (p>0.05). Both ammonium nitrogen and nitrate nitrogen concentrations peaked in autumn in both two vegetation areas, though the differences in ammonium nitrogen and nitrate nitrogen between two vegetation areas in the same sampling season remained statistically insignificant (p>0.05). Ecological network analysis results demonstrated the distinct influencing factors for nitrogen forms in Baiyangdian Lake at different space scales. The total carbon, organic matter, dissolved organic carbon, silt contents, and C/N ratios were identified as key factors influencing nitrogen forms on the whole-lake scale, while pH values, C/N ratios, total carbon, and organic matter were the key factors in different vegetation areas on the sub-lake scales. The findings of this work will contribute to better understanding the effects of nitrogen cycling on water quality in the shallow lakes and to improving hydroecological functions and ecological services of these ecosystems.