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The growth status, root exudates, radial oxygen loss, and sewage purification effect of plants acclimated with sewage and cultured with a nutrient solution were studied by selecting <i>Acorus gramineus Aiton</i>, <i>Pistia stratiotes</i> L., and <i>Eichhornia crassipes (Mart.) Solms</i> with the same individual size. The results showed that the root oxygen secretion rate of the <i>Acorus gramineus Aiton</i> was higher in light and dark conditions. For a single plant species, the oxygen secretion rate under light conditions was much higher than that under dark conditions. The root oxygen secretion rate of <i>Acorus gramineus Aiton</i> was the highest (2.03 µmol O₂/h/plant), followed by <i>Pistia stratiotes</i> L. (1.68 µmol O₂/h/plant), and the root oxygen secretion rate of <i>Eichhornia crassipes (Mart.) Solms</i> was the lowest (1.15 µmol O₂/h/plant). After a period of adaptation, plants showed strong removal effects on COD, NH₃-N, TN, and TP. The removal intensity was in the order of <i>Acorus gramineus Aiton</i> > <i>Pistia stratiotes</i> L. > <i>Eichhornia crassipes (Mart.) Solms</i>; the higher the temperature, the bigger the removal rate. These results were consistent with <i>Acorus gramineus Aiton</i>‘s organic matter secretion and radial oxygen loss, which were better than those of <i>Pistia stratiotes</i> L. and <i>Eichhornia crassipes (Mart.) Solms</i>. Three kinds of plants had better COD removal effects in an acidic environment and better TP removal effects in an alkaline environment. The results show that using the <i>Acorus gramineus Aiton</i> can achieve better remediation of polluted water bodies.