In order to verify the characteristics of vegetation structure in Jeolgu valley, Nakdongjeongmaek, we set up 29 plots(each plot area is $10m{ imes}10m(100m^2)$. The survey site is located in around the valley and its range is about 3km section. The forest vegetation communities were analysed by TWINSPAN classification. The results of communities were classified 5 types such as Pinus densiflora community, deciduous broad-leaved tree community, Quercus variabilis community, Quercus mongolica community, Larix leptolepis community. The deciduous broad-leaved tree which prefer to moist environment and Quercus spp. has dominant in around the valley and the northern slope. In addition, Larix leptolepis community expect to maintain the present status for a while. However, the under story of Larix leptolepis community have expanded the influence of deciduous broad-leaved tree such as Fraxinus mandshurica, Morus bombycis, Acer mono and so on. Therefore, there will be developed next ecological succession by species of deciduous broad-leaved tree. The diversity index showed form 0.9665 to 1.2450. It were analyzed that diversity index of Jeolgu valley was higher than other places in Nakdongjeongmaek.