Abstract:Tilia amurensis and Fraxinus mandshurica are mainly natural associated tree species in Pinus koraiensis stands, Pinus koraiensis trees often develop into stand under the crown of these broadleaved trees.Therefore, study on the influence of mainly associated tree species on the growth of Pinus koraiensis is very important for understanding the community function of these tree specie and properly selecting associated tree species in building mixed forest of Pinus koraiensis. A lot of pot incubation tests were conducted in this study, in which Pinus koraiensis seedlings were incubated with leaf extracts of Tilia amurensis, Fraxinus mandshurica, Picea koraiensis, Pinus koraiensis or their leaf powder mixed in pot soil. Experimental results showed that leaves of Tilia and Fraxinus broad-leaved species could promot the growth of Pinus koraiensis seedlings obviously in comparison with needles of Pinus koraiensis and Picea koraiensis. For this reason, Tilia and Fraxinus were suggested as important associated tree species in planting Pinus koraiensis coniferous-broadleaved forest.