In order to understand the effect of the environment of tropical coral islands on plant growth, the ecological adaptability of three species grown in tropical coral islands was studied, including Cynodon dactylon, Acacia auriculaeformis and Casuarina equisetifolia. The results showed that the antioxidant enzyme activities, such as SOD, CAT and POD, and proline content in three species grown in coral islands increased significantly (P < 0.05) compared with the same species grown in Seedling Base in Wenchang, Hainan Province. The malondialdehyde content in leaves of A. auriculaeformis and C. dactylon grown in coral islands also significantly increased (P < 0.01), while it had no difference in C. equisetifolia. Therefore, it was indicated that these species would adapt well to the harsh environmental conditions on the coral island through enhanced activities of antioxidant enzymes and increased contents of osmotic adjustment substances.