Employing the releve´ method of Muller-Dombois & Ellenberg and Braun-Blanquet, 100 plots were sampled in the Quercus mongolica community of Mt. Odae, Mt. Chumbong and Mt. Jungwang in Kangwon-do. To analyze the data, phytosociological method and TWINSPAN were used. 1. Quercus mongolica forests were recognized as Quercus mongolica-Acer pseudosieboldianum community group, and were classified into Quercus mongolica - Carpinus cordata community, Quercus mongolica Acer pseudosieboldianum typical community, Quercus mongolica -Lespedeza maximocoiczii community and Quercus mongolica - Abies nephrolepis community by phytosociological method. Quercus mongolica - Carpinus cordata community was subdivided into Acer mandshuricum subcommunity and typical subcommunity. 2. According to the classification of TWINSPAN, it was categorized into five groups, such as Quercus mongolica - Acer mandshuricum community, Quercus mongolica - Carpinus cordata community, Quercus mongolica -Acer pseudosieboldianum community, Quercus mongolica -Lindera obtusiloba community, and Quercus mongolica - Abies nephrolepis community. 3. Since the results of phytosociological community classification, which identify five groups of the community, were consistent with that of TWINSPAN, it proved that these two methods could be complement when one do a community classification.