Syntaxonomy and Synecology on Quercus variabilis forests in Daecheong-dam basin was carried out using the methods of Braun-Blanquet phytosociology. 6 syntaxa classified as species compositions described were Quercus variabilis community, Platycarya strobilacea-Quercus variabilis community(typicum subcommunity, dictamnus dasycarpus subcommunity), Quercetum variabili-serratae, Zelkova serrata-Quercus variabilis community and Dendranthema boreale-Quercus variabilis community. All syntaxa were shown habitat environmental conditions including steep inclination of more than 30°, high rock exposure rate of more than 50% and South-facing slope. These communities excepting Dendranthema boreale-Quercus variabilis community classified as natural vegetation were identified as low emergence rate of annual plants and species compositions composed native species, so it was confirmed that relatively natural succession were proceeding well. Quercetum variabili-serratae and Dendranthema boreale-Quercus variabilis community distributed forested hillslope of open water edge were representative Quercus variabilis syntaxa in Daecheong-dam basin.