Abstract: To investigate the effects of long-term nitrogen (N) and phosphorus (P) inputs on the seed germination characteristics of Suaeda salsa communities, we conducted a germination experiment using seeds collected from field plots with varying N and P supply levels (low, medium, high) and supply ratios (5:1 and 15:1) at the Coastal Wetland Ecological Research Station of the Yellow River Delta, Chinese Academy of Sciences. A filter paper-based Petri dish germination assay was employed to examine seed germination percentage, germination rate, seedling radicle length, and seedling biomass under different salinity conditions, against the background of long-term N and P inputs. Our results showed that long-term N and P input significantly affected seed germination and early seedling growth of Suaeda salsa. Seeds collected from plots with different N and P supply levels displayed significant differences in germination percentage, germination rate, and radicle length of early seedlings. Seeds from plots with medium and high N and P supply levels exhibited higher germination percentages and faster germination rates, while early seedling radicle growth after seed germination was better in plots with lower levels of nitrogen and phosphorus supply. Nevertheless, seedling biomass was not significantly affected by the change of N and P supply levels. When examining the effects of different N : P supply ratios, no significant differences were observed in germination percentage and germination rate. However, early seedling radicle length and biomass differed significantly between these two N : P supply ratios, with the 5:1 N : P ratio promoting greater radicle elongation and biomass accumulation. Notably, seeds collected from plots with a medium N and P supply level and an N : P ratio of 5:1 exhibited the best overall performance in terms of germination percentage, germination rate, and early seedling growth. Salinity stress had a significant effect on seed germination percentage, germination rate and early seedling growth. Both germination percentage and germination rate decreased with increasing salt concentrations; however, seed germination percentage under salinity levels ≤300 mmol/L was not significantly different from that under the control (0 mmol/L NaCl). Seedling radicle length and biomass exhibited a biphasic response to salinity, with low salinity levels promoting growth and high salinity levels inhibiting it. The interaction of nutrient supply level, N : P ratio, and salinity had a significant effect on early seedling growth, but not on seed germination. The results of this study demonstrate that in coastal wetlands, long-term nitrogen and phosphorus inputs significantly affect the seed germination characteristics of Suaeda salsa communities. Appropriate levels and ratios of nutrient supply can effectively promote seed germination and early seedling growth. These findings will contribute to a more comprehensive assessment of the impacts of long-term nitrogen and phosphorus enrichment on Suaeda salsa communities, and provide a scientific basis for the conservation and management of coastal wetlands.