Flooding is detrimental to terrestrial plants, usually reducing growth and survival rate. The negative impact of flooding on terrestrial plants is mainly attributed to the low oxygen content in water environment, which may result in energy crisis for terrestrial plants. Slow diffusion and relatively low solubility of oxygen in water lead to low oxygen content in water. Terrestrial plants live in the aerial environment with plenty of oxygen and have a suit of adaptations to such environment. To date, few studies have investigated whether the growth and survival of terrestrial plants, when completely submerged, are affected by the content of dissolved oxygen in water. In this study, using Alternanthera philoxeroides and Hemarthria altissima as model organisms (an invasive and a native terrestrial plant species, respectively, in the Three Gorges reservoir area), we examined the growth, survival, and non-structural carbohydrates of these plants when subjected to complete submergence with high (6.73 mg/L) and low level of dissolved oxygen (0.69 mg/L) in water. The following results were found in this study:(1) The level of dissolved oxygen in water had a significant influence on the survival of A. philoxeroides and H. altissima subjected to complete submergence. After the 30-day submergence treatment, the number of plants with undamaged stems, the number of surviving leaves, and the total plant biomass were higher in A. philoxeroides and H. altissima submerged in water with high dissolved oxygen content than in plants submerged in water with low dissolved oxygen content. (2) The level of dissolved oxygen in water affected the growth of completely submerged A. philoxeroides and H. altissima. Thus, A. philoxeroides submerged in water with high dissolved oxygen content showed pronounced stem elongation and adventitious roots formation compared to plants submerged in water with low dissolved oxygen content. Similarly, H. altissima produced more adventitious roots when submerged in water with high dissolved oxygen content. (3) High dissolved oxygen content in water reduced the carbohydrate consumption in completely submerged A. philoxeroides and H. altissima. Plants from both species had higher content of non-structural carbohydrates when completely submerged for 30 days in water with high dissolved oxygen content than in water with low dissolved oxygen content. (4) A. philoxeroides was more tolerant to complete submergence than H. altissima, which was more apparent when the plants were submerged in water with high dissolved oxygen content. Our study showed that, compared to the native species H. altissima, the invasive species A. philoxeroides is better adapted to unfavorable environmental conditions and exhibits higher submergence tolerance.