Abstract: To understand the formations of plant diversity and maintenance mechanisms of islands along the coast of Fujian Province, the data of prior expeditions on inhabited islands and of plant diversity, population density and environmental factors from uninhabited islands are explored. The plant diversity and its key influencing factors on 19 islands from both the taxonomic and phylogenetic perspectives are studied. It results that area of island is the main factor influencing species and phylogenetic diversity of island plants besides certain impacts by latitude and average annual precipitation. Phylogenetic structures of plant communities on 19 islands tend to be clustered possibly due to the impacts of environmental changes and human activities. Inter-island geographic distance has no significant effects on phylogenetic beta diversity among plant communities on each island. Islands with higher phylogenetic diversity that should be protected with higher priority include Dongshan Island, Culu Island, Nanri Island, Meizhou Island, Xiamen Island, Pingtan Island and Sandu Island. Conservation and exploitation strategies on islands based on their biodiversity situations and functional positions are proposed. This study can provide not only a valuable model for multi-level diversity assessment and analyses of assembly mechanisms of plant community, but also a theoretic support for conservation management strategies.