The vascular plants in the Ohseosan and the Bongsusan, Chungnam were listed 439 taxa (9.0% of all 4,881 taxa of vascular plants); 95 families, 268 genera, 339 species, 5 subspecies, 75 varieties and 20 forms. Furthermore, the Ohseosan were listed 339 taxa and the Bongsusan were listed 306 taxa. So, Hemicryptophytes (H) were 107 taxa (24.4%), Therophytes (Th), Geophytes (G) same as were 82 taxa (18.7%) showed high proportional ratio in life form. Based on the list of rare plants, 4 taxa; Aristolochia contorta, Viola albida, Scutellaria insignis (LC) and Scrophularia koraiensis (DD) and endemic plants, 8 taxa; Aconitum pseudolaeve, Ajuga spectabilis, etc. Based on the list of specific plants, 35 taxa; Wisteria floribunda for. floribunda in class Ⅳ, 5 taxa (Scutellaria insignis, Scrophularia koraiensis, etc.) in class Ⅲ, 5 taxa (Acer triflorum, Cymopterus melanotilingia, etc.) in class Ⅱ, 24 taxa (Pyrus ussuriensis var. ussuriensis, Campanula punctata, etc.) in class Ⅰ. Based on the list of naturalized plants, 9 families, 20 genera, 24 taxa (Persicaria orientalis, Carduus crispus, etc.) and ecosystem disturbing plants were Rumex acetocella, Ambrosia artemisiifolia. Naturalization rate was 5.5% of all 439 taxa of vascular plants and urbanization index was 7.5% of all 321 taxa of naturalized plants. In particular, for rare plants, in and ex-situ conservation of genetic resources must surely be done, by preserving present natural habitats, discovering additional natural habitats and securing seeds. Moreover, ecosystem disturbing plants require long-term monitoring and consistent management, since not only do they disturb the ecosystem in competition with Korean native species, but damage humans, too.