Abstract: In order to evaluate the impact of changes in atmospheric and water environment on aquatic plants, we study the photosynthesis physiological of V. natans under different phosphorus and CO₂. The results showed that the fluorescence V_j、M_o of V. natans reduced when the concentration of phosphorus in the water was at a high level, but the ABS/CS_o, DI_o/CS_o, TR_o/CS_o, RC/CS and P_ET increased at the same time; high concentration of CO₂ significantly reduced V_j, ABS/RC, DI_o/RC, ABS/CS_o and DIo/CS_o of V. natans, but improved the level of ψ_o, φ_Eo, ET_o/RC, PI_ABS, F_v/F_m, P_TR and P_ET. There was a significant impact of phosphorus and CO₂ on V_j, M_o, ψ_o, TR_o/CS_o and RC/CS of V. natans. The change of phosphorus and CO₂ concentration could significantly affect the photosynthetic physiological of V. natans; high concentration of CO₂ can improve the performance of photosynthesis of V. natans leaves by promoting photochemical propertieselectron, transfer process and optimizing the distribution of energy among PSⅡ; while high concentration of phosphorus have significant promotion on the donor and acceptor of PSⅡ, and it also improved the electron transfer properties of V. natans. Moreover, there was an interaction of phosphorus and CO₂ on photosynthetic physiological of V. natans.