From February 2021 to March 2022, the 11 major islands (Gageo-do, Manjae-do, Sangtae-do, Jungtae-do, Hatae-do, Hong-do, Heuksan-do, Jang-do, Yeongsan-do, Damul-do, and Daedun-do) in the Shinan-gun Heuksan area were investigated. The current status of flora and distribution of Dangsan trees was investigated, focusing on the Dangsan forest in 24 villages in the area. A total of 91 taxa were identified, including 47 families, 80 genera, 84 species, and 7 varieties of vascular plants in the Dangsan forest in the Heuksan region of Sinan-gun. This corresponds to 1.86% of the 4,881 taxa of domestic vascular plants, of which 9 taxa (9.9%) for ferns and 79 taxa (86.8%) for angiosperms were identified. And among angiosperms, monocotyledons were in 13 taxa (16.5%) and dicotyledons were in 66 taxa (83.5%). There were a total of 34 families and 58 taxa of specific plants identified in Dangsan Forest. Grade Ⅴ is 1 species of Podocarpus macrophyllus, Grade Ⅳ is a total of 4 taxa, such as Quercus myrsinifolia, Daphniphyllum teysmannii, Angelica japonica, and Hosta yingeri, Grade Ⅲ is a total of 32 taxa such as Arachniodes aristata, Dryopteris pacifica, Dryopteris nipponensis, and grade Ⅱ is Peucedanum japonicum. A total of 20 taxa were found, including one type of oily greens, grade I, such as Lemmaphyllum microphyllum, Lepisorus thunbergianus, and Carpinus turczaninowii. Also, among the major specific plants, taxa 1 (Hosta yingeri) and taxa 2 (Hosta yingeri, Ardisia crenata) were investigated for endangered species, but not for endangered species. As a result of a complete investigation of the circumference of the Dangsan tree in the Dangsan forest in the Heuksan region of Sinan-gun, focusing on the tree layer(subtree layer), the total number of species that appeared was Castanopsis sieboldii, Machilus thunbergii, Camellia japonica, Celtis sinensis, Pinus densiflora, Pinus thunbergii, Neolitsea sericea, and Daphniphyllum teysmannii. A total of 29 trees including Eurya japonica, Litsea japonica, Dendropanax trifidus, Ligustrum japonicum, Quercus myrsinifolia, Cinnamomum japonicum, Zanthoxylum ailanthoides, Carpinus turczaninowii, Rhaphiolepis indica var. umbellata, Pittosporum tobira, Quercus acuta, Euonymus japonicus, Kalopanax septemlobus, Mallotus japonicus, Aphananthe aspera, etc. It is a state in which a dog type of Dangsan tree is composed. A total of 896 Dangsan trees were investigated. Among them, Castanopsis sieboldii(295 trees, 33%), Machilus thunbergii(193 trees, 22%), Camellia japonica(140 trees, 16%), and Celtis sinensis(78 trees, 9%) were investigated. pine (44 trees, 5%), gom Pinus densiflora(34 trees, 4%), and Neolitsea sericea(22 trees, 2%) showed a high distribution ratio. Among the Dangsan trees surveyed in all 24 Dangsan forests, Dangsan trees with a relatively high frequency of appearance were pine Castanopsis sieboldii(15 times, 62%), Machilus thunbergii(19 times, 79%), Camellia japonica(16 times, 66%), Celtis sinensis(11 times, 46%), Pinus densiflora(9 times, 37%), Pinus thunbergii(5 times, 20%), and other species such as Neolitsea sericea, Daphniphyllum teysmannii, Eurya japonica, and Litsea japonica showed relatively high frequency of appearance. Of the total 91 taxa surveyed in Dangsan Forest, 63.7% (58 taxa) were found to be phytogenetically specific plants. This is because the geographical distribution area and habitat of the constituent species constituting the Dangsan forest are high, and the major Dangsan trees are recognized for their ecological conservation value, so systematic protection measures and long-term monitoring of the Dangsan forest are required. The Heuksan region of Sinan-gun has relatively excellent natural scenery, and in establishing effective management measures for Dang forests with high conservation value for each major island, management plans should be established according to the characteristics of Dang forests for each village.