Abstract: In March of 2015, 1-year container seedlings of Liquidatubaformosanawere pot cultured atgreenhouse in Hangzhou, Zhejiang province.Experiments were conducted on effect of root and crown flooding on growth and photosynthesis.The results indicated that height growth and biomass accumulation of flooding seedlings was evidently higher than that of CK.Morphological changes wereobserved on treated L.formosanaseedlings, such as decreaseof leaf area, largerstem andlenticels.The activity of photosynthesis of treated seedlings increased obviously at beginning, resulting larger net photosynthetic rate, decrease of light compensate point and increase of light saturation point, and then decreased with the durationof water logging.The diurnalchange curve of Pn changed into single peak with earlier photosynthetic inhibition.Photosynthesis capacityof seedlings treated by water logging decreased significantly45 days later.The experiment resulted thatL.formosanaseedlings could be resistant to 60 days of crown logging, indicating strong resistance against water logging.