Abstract: A flooding simulation experiment was conducted to detect the effects of flooding on photosynthesis, growth and nutrient concentrations of Cynodon dactylon. Two flooding-depth levels, surface flooding (SF) and total flooding (TF) were imposed, and compared with control (CK). Net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (T_r) and stomatal limitation (L_s) of C. dactylon under SF were significantly lower than those for the CK treatment, while the intercellular CO₂ concentration (C_i) was significantly higher. However, water use efficiency (WUE) did not differ significantly between SF and the CK treatment. Under SF, root length, root surface, root volume, branch number, leaf number, root biomass, leaf biomass and root∶shoot ratio were all significantly reduced, whereas plant height, base diameter, stem biomass and total biomass did not differ significantly between SF and CK. Under TF, root length, root surface, root volume, plant height, branch number, leaf number, root biomass, base diameter, stem biomass and total biomass were also significantly lower than those of CK. Compared to CK, root nutrient concentrations (N, P, K, Fe, and Mn) of C. dactylon under SF and TF were increased, whereas Cu content was significantly decreased. Leaf concentrations of Fe and Mn under SF were significantly increased, but the contents of P, K and Cu under SF were significantly decreased, compared to CK. Thus flooding resulted in significant reductions in photosynthesis, growth, and uptake of nutrients of C. dactylon. The reduction of leaf concentrations of P, K, and Cu and the rise in leaf concentrations of Fe, and Mn could account for the reduction in P_n. However, C. dactylon was able to improve the absorption of N, P, and K, promote stem elongation and maintain a high net photosynthetic rate to cope with flooding. Additionally, when flooded, leaf N and P could potentially be directly released into the water on leaf fall, which could increase the risk of eutrophication in waterways.