Abstract: Based on field simulation experiment of oneyearold seedlings during 60 days, the preliminary research, aimed to understand the waterlogging or flooding tolerance and adaptation mechanisms of three different three species(i.e. Taxodium distichum, Carya illinoensis, Sapium sebiferum), was conducted. The results were as follows:(1) In differn level, the three tree species all showed perfect ability tolerant to waterlogging or flooding. Under the first 30 days of waterlogging and flooding stress, superoxide dismutase (SOD) activity, ascorbic acid peroxidase (POD) activity, ascorbic acid (ASA) content, reducing glutathione (GSH) content, proline(Pro) content and soluble protein (SP) content in the leaves or roots of the three tree species, both showed significant rise. (2)However, there was a remarkable different in their waterlogging or flooding resistant ability among the three tree species. T. distichum had the strongest tolerance to waterlogging or flooding, C. illinoensis the middle, and S. sebiferum the most weakest. During the first 50 days of waterlogging or flooding stress, the average increment of SOD, ASAPOD, ASA, GSH activeness and Pro and SP content in the leave or roots of T. distichum were not only greatly higher than the ones in other two tree species, but also kept the continuing growth tendency and maintained at high levels, while those indexes in other two tree species showed a trend of sharp decline in 30 days of waterlogging or flooding. (3) For the 3 trees, water resistant mechanism was probably related to their regulation ability of seedling structure, antioxidant enzymes and antioxidant synthesis, etc.