This study examined the coastal sand dune vegetation before and after the construction of an embankment on Anmado Island in order to compare vegetation in relation to the development of islands. A total of 24 species distributed on the sand dunes. 18 species were found to be in common before and after the construction of the embankment, which included Vitex rotundifolia, Imperata cylindrica var. koenigii, Zoysia sinica, etc. The species which were not found in this survey included Rumex japonicus, Setaria viridis, Portulaca oleracea, Artemisia japonica, Poiygonum aviculare, etc, and new species included Arena fatua, Carex boottiana, Lycium chinense, Leonurus sibiricus, Twills japonica, Solanum carolinense, etc. The washing away of sand brought about the changes in habitat and the increase in naturalized plants, which included Oenothera odorata, Lepidium apetalum, Bidens bipinnata, Erigeron canadensis, Datura stramonium, Xanthium strumarium, Arena fatua, Solanum carolinense etc. In addition, the disturbance to this habitat led to the changes in vegetation. The main plant communities in the surveyed site were classified as Vitex rotundifolia-Imperata cylindrica var. koenigii community, Zoysia sinica-Calystegia soldanella community and Messerschmidia sibirica community. The sand dune vegetation on Anmado Island changed with regard to the community and the composition of species after the construction of the embankment, due to the sand being severely eroded. While Vitex rotundifolia community and Commelina communis community were found before the construction of the embankment, they were replaced by Vitex rotundifolia-Imperata cylindrica var. koenigii community, Zoysia sinica-Calystegia soldanella community and Messerschmidia sibirica community, after the construction of the embankment.