In order to determine ecological niches of forests in Mt. UnJang, the studies were analyzed on the methods of TWINSPAN and DCCA ordination. The results are summarized as follows : Six communities determined by TWINSPAN : Fraxinus mandshurica, Cornus controversa, Acer mono, Carpinus tschonoskii, Carpinus tschonoskii - Quercus variabilis, and Cuercus mongolica community . In the relations of major community and environmental factors, Fraxinus mandshurica, Cornus controversa, and Acer mono community were distributed valley or evenness in the rich of organic matter. Elevation was high comparatively. Carpinus tschonoskaii and Carpinus tschonoskii - Quercus variabilis community were distributed in the low elevation, in rich of MgO and CaCO₃. Quercus mongolica community were distributed in the high elevation, in low of MgO, CaCO₃,. The factors in influencing community distribution were elevation. The importance value in all the quadrats sampled, Quercus mongolica recorded the highest and the next values then came those Cornus controversa, Acer mono, Fraxinus mandshurica, Quercus variabilis, Carpinus tschonoskii, Acer pseudosieboldianum Lindera erythrocarpa, Styrax obassia and Lindera obtusiloba in the orders.