The purpose of this study is to investigate distribution of the vegetation and insects of coastal dunes in the Yangyang area. The field survey was carried out Osan and Dongho coastal dunes during the period from June to July 2008. A total of 68 taxa were identified including 30 families, 60 genera, 59 species, and 9 varieties. 1 species(Glehnia littoralis) was recorded as designated rare plant of Korea Forest Service. The naturalized plants were 8 families, 13 species. The urbanization rate of naturalization index was 4.8% and 19.1% respectively. The land insect appeared with the 10 order, 23 families including 10 Korean specific species and 16 environmental indicator species for coastal dune. The species in Order Coleoptera was most, followed by Hemiptera, Orthoptera and Odonata respectively.