This study has been carried out to classify forest vegetation in south and north slopes of Donghaksa valley for supplying basic data for conservation and restoration of the valley. With the phytosociological method, the forest of the south and north slopes of Donghaksa valley was classified as four groups; Quercus variabilis community, Quercus mongolica community, Pinus densiflora community and Carpinus laxiflora community. The dominant species were found in the order of Pinus densiflora, Quercus variabilis, Carpinus laxiflora, and Quercus mongolica. Comparing the north and south slopes, Quercus variabilis were the highest dominant species in the south and Carpinus laxiflora in the north. Pinus densiflora were the next dominant species in both south and north slopes. According to the DBH analysis result, Pinus densiflora and Quercus variabilis had density of normal distribution style among the entire community. Therefore, their dominance are expected to continue for now. But, Quercus mongolica and Carpinus laxiflora are expected to extend their influence in the future in terms of competition with Pinus densiflora. The correlation between each community and the environment according to DCCA ordination was examined in this study. The result told us that Quercus variabilis is distributed mainly on the south slope in a mid-steep and mid-altitude area. Quercus mongolica community appeared on the north slope in the steep high-altitude area that has high percentage in total nitrogen and CEC. Pinus densiflora community is distributed on both south and north slopes in a gentle slope and low-altitude area. Carpinus laxiflora is distributed on the north slope in a mid-steep and mid-altitude area.