The total number of vascular plants found in the Ganghwado and nearby island regions (Seokmodo, Gyodongdo, Boreumdo, Jumundo) was 107 families, 388 genera, 616 species, 5 subspecies, 81 varieties, 11 forms. and 713 taxa. Among these, the area with the highest number of taxa was Ganghwado at 92 families 279 genus 454 taxa, followed by Seokmodo at 90 families 271 genera 442 taxa, Gyodongdo at 82 families 228 genera 338 taxa, Boreumdo at 66 families 196 genus 286 taxa and Jumundo at 145 taxa. Among the studied plants, there were 6 taxa of endemic plants to Korea, 11 taxa of rare species, and 14 taxa of Degree III or higher in terms of ecological significance. A total of 94 taxa of naturalized plants were confirmed, marking 13.2% of all the taxa studied. As a special note, ecologically detrimental species, such as Ambrosia trifida and Sicyos angulatus were observed in Boreumdo and Jumundo respectively, which is a reason for concern of rapid spread.