This study was first performed since 1933 to investigate the flora of Oˇchoˇng Island located in the middle part of Yellow Sea. A number of vascular plants recognized through in this survey were 319 taxa belonging to 78 families, 213 genera, 279 species, 38 varieties and 2 forma in which 38 species were newly recorded and 26 species of evergreen plant were identified. The Pteridophyta distributed in this island were 10 species and the naturalized plants were 4 species. And the coefficient of cryptogram(Pte-Q) and Urbanization Index(UI) as to the destruction degree of natural vegetation showed a value of 0.81, 3.64 respectively. Some noticeable species were Kadsura japonica, Castanopsis cuspidate var. thunbergii, Dendropanax morbifera, and Ficus stipulate and Oˇchoˇng Island was considered as the northern limit of distribution of these species.