With the nonaeration(Ⅰ) and aeration(Ⅱ) conditions of two aquatic plant purifyingtanks, the changes of plant physiological traits including the activities of POD, CAT, and the contents of SP, Chla,and the main physical water quality in a day at different times, were observed. Correlation between diurnal variation of plant physiological traits and removal efficiencies of CODCr,NH4+-N,TP were analyzed, and the effect of aeration to plant physiological traits and the purifying effect were studied. The results showed that the plant physiology and the water quality index were affected by the light intensity changes to some extent. The physiological traits of 〖WTBX〗Nymphaea tetragona〖WTBZ〗 had positive correlations with the removal efficiencies of CODCr,NH4+-N, TP. Aeration affected the activities of POD, CAT and the contents of SP, Chla significantly; the water quality of two conditions of purification tanks were affected by the variation of light intensity. The content of DO and the removal efficiencies of CODCr,NH4+-N, TP in the conditionⅡexceeded the conditionⅠby 2.54 mg/L, 21.0%, 16.6% and 14.1%, respectively.