Abstract: Taking 7 petunia lines（ethylene response factor PhERF2-overexpressed lines C,D,I,RNAi-PhERF2 silent lines 1 A,1 B,4 B and their wild-type（WT））as materials, the phenotypes of overexpression lines, silent lines and wild-type of Petunia hybrid PhERF2 gene in waterlogging environment were compared, and the activities of antioxidant enzymes and anaerobic respiratory enzymes were measured to explore the effect of ethylene response factor PhERF2 on waterlogging tolerance of Petunia hybrid.The results showed that, after 72 hours waterlogging treatment, the malondialdehyde（MDA） contents of C,D and I were only 33.33%,45.10% and 58.50% of those of the wild type, while the activities of superoxide dismutase（SOD）,peroxidase（POD） and catalase（CAT） were generally higher than those of the silent type and the wild type.Higher antioxidant enzyme activity was beneficial to enhance waterlogging resistance of plants.The results showed that the overexpressed lines could adapt to waterlogging stress by increasing antioxidant enzyme activity and reducing MDA content.The activity of dehydrogenase（ADH）,lactate dehydrogenase（LDH） and pyruvate decarboxylase（PDC） in the roots of 7 lines showed a trend of first increasing and then decreasing, among which the LDH activity of C,D and I was significantly lower than that of the silenced lines and wild-type lines on the whole.The LDH content of the three lines was 51.3%,78.0% and 58.8% of 0 hours respectively at 72 hours after waterlogging treatment, the increasing of anaerobic respiration enzyme activity could promote the adaptation of plant roots to hypoxic environment.In the 4-day waterlogging treatment, the phenotypic symptoms of waterlogging damage at 4 B were the most serious, and all the leaves were wilted, saggy and yellowed and dried.Combined with the above results, the phenotypic symptoms of waterlogging were the most serious in silenced lines, the antioxidant enzyme activity and anaerobic respiration enzyme activity of over expressed lines were higher than those of wild-type and silenced lines.It indicated that overexpressed lines may have a stronger ability to clear reactive oxygen species and reduce the toxic effects of metabolites such as lactic acid and ethanol on cells,in order to alleviate the damage of plants under adversity,it shows that plants have stronger tolerance to water logging stress.The results of this study preliminarily demonstrate that ethylene response factor PhERF2 positively regulates plant waterlogging tolerance．