The Three Gorges Reservoir (TGR) is the largest man-made reservoir ever built in the world with enormous hydro-fluctuation zone. Operation mode of the Three Gorges dam totally reversed the natural seasonality of flooding in hydro-fluctuation zone, and increased its submergence depth and duration. Therefore, the evolution of hydro-fluctuation zone ecosystem, especially the nutrient adaptation strategies and homeostasis characteristics of plants, referring to the ecological security of the Three Gorges Reservoir, have been widely concerned. However, due to the wide distribution and complex topography of the hydro-fluctuation zone in TGR, the adaptation characteristics of plants in different habitats are still not well understood. In this study, 28 sampling plots from upstream to downstream in TGR were selected for investigation of nutrient and ecological stoichiometry characteristics of Cynodon dactylon (most widely distributed species in hydro-fluctuation zone of TGR) and its native soil. The 28 sampling sections were divided into five groups with the topographic differences (0-5°, 5-10°, 10-15°, 15-20°, >20°) for exploring the effect of slope on ecological stoichiometry and homeostasis of C. dactylon-soil system. The results showed as follows:(1) the slope had significant effects on soil nutrients and stoichiometric characteristics. The contents of organic carbon (SOC), total nitrogen (STN), total phosphorus (STP), and available nitrogen and phosphorus (SAN and SAP) in soil all decreased with the increase in slope. Particularly the carbon, nitrogen and phosphorus in soil sampled in surveyed plots with slope below 10° were significantly higher than those in the surveyed plots above 10°. C:N and C:P ratios in soil samples showed slightly decrease with slope increasing, while N:P had no response to slope changing, indicating that the loss of soil nutrients were sensitive to slope in the hydro-fluctuation zone and more unstable than organic carbon. (2) With the increase of slope, carbon (C) contents of C. dactylon showed a marked increase either in leaf, or in roots and stems. While nitrogen (N) and phosphorus (P) contents of C. dactylon decreased with the increase of slope observably. Lower C:N and C:P ratios in roots and stems of C. dactylon were found in the surveyed plots with low slope, while lower N:P ratio was found in those plots with higher slope. It highlighted that C:N and N:P ratios in leaves of C. dactylon were insensitive to slop changing, suggesting that C. dactylon could stabilize preferentially the ecological stoichiometry of leaves in stressful environments relating to slope. (3) The slope had a significant negative correlation with SOC, STN and SAN contents. Meanwhile, STN had significant correlations with plant stoichiometric characteristics of C. dactylon, signifying the soil nitrogen loss caused by slope change was the main mechanism of slope influencing stoichiometric characteristics of C. dactylon. (4) The nutrient homeostasis in C. dactylon-soil system showed a tendency of C>P>N. And the homeostasis of stoichiometric ratio showed C:P>C:N>N:P. Slope changing in hydro-fluctuation zone of TGR significantly influenced the stoichiometric ratio homeostasis for C. dactylon-soil system, showing higher slope with low homeostasis. Our study suggested that topographic complexity for hydro-fluctuation zone of TGR was important for the nutrient strategy of C. dactylon, while C. dactylon could effectively maintain the stoichiometric balance and had better homeostasis, being a dominant species for vegetation restoration and conservation in hydro-fluctuation zone of TGR.