Abstract: In order to reveal the physiological response mechanism of Barringtonia acutangula to flooding stress, the range of flooding duration of B. acutangula was obtained. Half-day tide was simulated. B. acutangula seedlings were completely submerged under different flooding time in the greenhouse, and the growth index and physiological indexes of the plants were determined. The results show that after 28 days of fresh water flooding treatment, the seedlings of B. acutangula were all green-leaved plants, and the survival rate is 100%. The effects of different flooding duration on plant height, ground diameter, total leaf growth and growth rate are not significant. The effects of different flooding days on plant height, ground diameter and leaf growth rate are extremely significant. With the increase of flooding time, the SOD activity of seedling leaves show a steady trend when the flooding time is 0-6 h/d. POD activity and MDA content increase at first and then decrease. The difference of POD activity and MDA content is not significant compared with CK, but proline content decreased significantly. The SOD activity increases significantly when the flooding time is increased to 8-12 h/d, and reaches the maximum at 10 h/d. The content of proline is significantly different from CK at 10 h/d and 12 h/d of flooding. It can be seen that fresh water flooding for 0-12 h/d do not affect the growth and development of B. acutangula stamen plants. The critical time of drowning stress for B. acutangulaseedlings is 8 h/d under full-flooded fresh water environment, and the minimum suitable time for drowning is 0-12 h/d.