This study was carried out to classify forest vegetation structure of Mt. Gaya from April to October in 2006 using phytosociological analysis methodology of Z-M schools. One hundred study sites(quadrat) were surveyed in the area. The forest vegetation was classified into 3 community groups such as Pinus densiflora community group, Cornus controversa community group and artificial forest group. P, densiflora community group was subdivided into 4 communities such as Rhododendron schlippenbachii community. Salix gracilistyla community, Meliosma oldhamii community and P. densiflora typical community. R. schlippendbachii community was subdivided into Potentilla dickinsii group(subdivided into Carpinus coreana subgroup and Melandrynum firmum subgroup) and R. schlippenbachiitypical group. Cornus controversa community group was also subdivided into 4 communities such as Hovenia dulcis community, Quercus aliena community, Ribes maximowicianum community and C. controversa typical community. Artificial forest type indicated 3 communities such as Larix leptolepis community, Pinus rigida community and Castanea crenata community. Accordingly, the vegetation pattern of the surveyed areas were classified into 3 community groups, 11 communities, 2 groups, and 2 subgroups and the forest vegetation was classified into 13 units in total. It is also believed that C. coreana subgroup and M. oldhamii community could be a source for a significant basic data for making vegetation hierarchy and forest distribution zone in the Korean peninsula. H. dulcis community was also considered to be one of the important genetic resources; therefore, those distribution areas are required to be institutionally protected and managed in the near future.