Abstract:In order to understand the resistance of Morinda citrifolia, its eco-physiological characteristics were studied grown in Dongdao of Xisha Islands, China. The results showed that M. citrifolia was a heliophyte with strong competitive ability for light resources. The contents of N, P and chlorophyll b were high in leaves, which was an important character in adaptation to tropical costal island habitat. M. citrifolia had big sponge tissue and stoma density with small vessel diameter. The content of malondialdehyde, activities of superoxide dismutase and catalase were high with low proline content, which indicated that M. citrifolia had strong drought resistance. In addition, N content in soil was low with high salt content. So, M. citrifolia could be used as one of the tool species in the vegetation restoration in tropical coast.