[Objective]Cynodon dactylon is important component and dominant species in ecosystem of the water-level fluctuation zone (WLFZ) of the Three Gorges Reservoir, which is the largest hydropower project in the word. Investigation on the spatial distribution patterns and correlations of nutrient and stoichiometric characteristics between C.dactylon and its periradical soil holds significant importance in comprehending nutrient cycling as well as species adaptation features within the WLFZ.[Methods]This study conducted a field investigation of C.dactylon and its periradical soil across 16 sections in the WLFZ of the Three Gorges Reservoir Area from Banan to Yichang. The carbon, nitrogen, and phosphorus contents in plant organs (roots, stems, leaves) and soil were analyzed to explore the spatial heterogeneity and interrelationships of the ecological stoichiometry characteristics between C.dactylon and soil.[Results](1) The soil in the WLFZ associated with C.dactylon demonstrated a distinct "nitrogen-poor and phosphorus-rich" characteristic with significant spatial variations in nutrient contents and stoichiometric ratios. Specifically, soil organic carbon, total nitrogen, total phosphorus, C/N ratio, and C/P ratio exhibited a consistent increase from upstream to downstream sections. while, N/P ratio showed relatively stable, indicating synchronized spatial changes in nitrogen and phosphorus contents in the soil. (2) From upstream to downstream of WLFZ, the carbon contents in various organs of C.dactylon exhibited a decreasing trend, while nitrogen and phosphorus contents showed significant increasing patterns. This trend could be attributed to intensified sedimentation and resultant higher soil nutrient supply levels in the downstream WLFZ with the prolonged flooding time. Notably, the nitrogen content in the leaves demonstrates a degree of spatial stability, suggesting that C.dactylon could absorb nitrogen efficiently and meet its leaf nitrogen requirements prioritizly under nitrogen-deficient conditions. (3) Generally low variations in the stoichiometric ratios in organs of C.dactylon were found. However, the variability in C/N and C/P ratios in roots and stems were slightly strong than that in leaves, suggesting that C.dactylon has evolved a strategy maintaining stable physiological functions in leaves. (4) There were significant correlations of the nutrient contents between C.dactylon and soil, with the nitrogen supply of soil being the key factor influencing the variation of nutrient contents in C.dactylon. The correlations of stoichiometric ratios between C.dactylon and soil is relatively weak. (5) C.dactylon in the WFLZ generally exhibited strong homeostasis with the homeostasis index decreasing from upstream to downstream.[Conclusion]In the context of changing water inundation patterns, the nutrient contents in C.dactylon and soil exhibit significant spatial variations and cooperative association, implying that the spatial evolution of soil nutrients has a profound impact on the ecological stoichiometry characteristics of C.dactylon. While, the C.dactylon exhibits limited spatial differentiation in stoichiometry, indicating its strong adaptability to the heterogeneous soil conditions through adjustments in nutrient demand strategy. The feedback relationships of stoichiometry between C.dactylon and soil may exhibit instability under periodic waterlogging stress in WFLZ.