Abstract: 【OBJECTIVE】The seasonal flooding stress was the main restriction factor for afforestation of Populus deltoides in beach land,the evaluation of flooding-tolerance ability through reliable properties was very important.【METHOD】The response of inner physiological characters,correlation among different characters and their genetic variation under flooding stress were studied objecting to Populus deltoides clones XL-75，XL-77，XL-90 and ck( I-69，Salix×jiangsuensis ‘J172’).【RESULT】Contents of chlorophyll, Soluble Protein and CAT activity of all clones under waterlogging stress were decreased totally compared to contrast. Content of MDA in I-69 was increased significantly compared with the contrast，Content of MDA in XL-75，XL-77，XL-90，J-172 in earlier time of waterlogging were decreased slightly compared with contrast and increased with sustain inundation. The SOD activity decreased obviously than CK in earlier time of waterlogging stress，but the POD activity rised obviously. With the waterlogging stress deepened，the SOD activity was rising one by one and the POD activity was declining one by one，both had obviously compensation on anti-oxygenation mechanism. Flooding within 30d，the ADH activity increased more obviously than CK. When flooding on 45d，the ADH activity of I-69 decreased 56.9% compared with CK，but the ADH activity of XL-75，XL-77，XL-90，J172 respectively increased 970.4%，279.1%，555.2% and 461.5% compared with CK.【CONCLUSION】The relative value of Chl，SOD，CAT had very remarkably positive correlation with the total biomass，and the heritabilities of Chl，SOD，CAT ranged from 0.5967 to 0.7743.It indicated that the variations of 3 traits were moderately or intensively inherited，and they could be used to evaluate the flooding-tolerance of populus deltoides clones.