Abstract: This paper aims to explore the physiological and morphological characteristics and response mechanism of riparian plants under water flooding stress.Dominant plant species, such as Cynodon dactylon, Hemarthria altissima, Alternanthera philoxeroides and Polygonum hydropiper, were collected from the riparian zone of the Le'an River and cultured indoor using soil pot methods.The water level was controlled by a toughened glass tank.Different water flooding stress conditions were set up as follows:control group, infiltration, half flooded and fully flooded.We measured the changes of chlorophyll contents, photosynthetic parameters, fluorescence parameters, fluorescence imaging and morphology at different periods of water stress, and analyzed the above indexes reflected in the level of community and the resilience response mechanism of the plant groups under the water flooding stress.Under the short-term water stress condition, our results showed that the degree of total chlorophyll(Chlt), net photosynthetic rate(P_n), transpiration rate(T_r), intercellular CO₂ concentration(C_i), maximum quantum yield(QY_max), plant height and leaf number of each plant were decreased compared with the control group.However, the average contents of Chlt, P_n and QY_max in the infiltration group were slightly higher than those of the control group.The concentration of intercellular CO₂(C_i) was elevated, while the values of non-photochemical quenching decreased first and then increased.The physiological and morphological indexes of the four plant species under the long-term water stress were comparable to the short-term water stress.The P_n and leaf number in the fully flooded groups were significantly decreased compared to the corresponding short-term water stress groups.The values of w(Chlt), P_n and leaf numbers of C.dactylon, H.altissima, A.Philoxeroides and P.hydropiper were significantly lower than those of the control group(P < 0.05).The significant difference values of the above three parameters for C.dactylon were 100%, 100% and 100%;the values for H.altissima were 67.9%, 63.8% and 62.3%;those for A.philoxeroides were 73.6%, 83.2% and 89.6%;and those for P.hydropiper were 54.5%, 100% and 100%, respectively.All plants of C.dactylon and P.hydropiper died in the fully flooded groups.The research suggests that there are different effects from water stress under the different water levels for the four plants, as well as the resistance of the plants to counteract the effect of water stress.