In this study, six hydrophyte species (Ceratophyllum demersum, Canna indica, Iris pseudacorus, Pistia stratiotes, Myriophyllum spicatum, and Eichhornia crassipes) were selected to investigate the effects of different Cd concentrations on the growth and water purification rates in order to identify species with the best Cd remediation effects. Additionally, a kinetic model of Cd adsorption by aquatic plants was determined using a regression method. The survival rate of the six species of aquatic plants under Cd stress was 100%. However, Cd stress inhibited the accumulation of biomass and nutrient elements in aquatic plants. Cd was mainly concentrated in the roots of aquatic plants. The simulation result of the kinetic model revealed that the exponential function model was most suitable for describing Cd removal, indicating that this model can be used to predict the degree of Cd purification by aquatic plants. The species E. crassipes and P. stratiotes were highly efficient in Cd removal, with an average removal rate above 88%. Thus, E. crassipes and P. stratiotes are species with potential for use in the remediation of Cd-polluted water in constructed wetlands and floating beds.