Abstract: Based on large scale data of plant distribution and climates factors, the floristic spectrum, principal coordinate analysis (PCoA) and cluster analysis and canonical correspondence analysis(CCA) were used to reveal the phytogeography distribution and climatic environment relationship of coastal islands in southern China. The results showed that: (1)The floristic viariations with latitude, compositions of tropical elements increase with droping of latitude, while those of temporate elements showed contrary patterns. The result is almost in accordance with distribution of climate belts; (2)Based PCoA analysis and cluster analisis, the main coastal islands floras were divided into 5 groups. The result indicated the distribution-types similarities at genus-level between islands and moutain. (3) CCA analysis showed that the mean temperature of January, anual mean temperature and latitude are the determining factors of phytogeography distribution of islands in China.