To explore the composition and interannual dynamics of tree seedlings in a broad-leaved Korean pine mixed forest, 600 25 m2 (5 m×5 m) seedling quadrats were set up in a 25-ha plot of the forest in Changbai Mountain. All seedlings in these quadrats were tagged, measured and identified to species. Based on three seedling censuses between 2006 and 2008, we analyzed species composition, spatial distribution, and inter-annual dynamics of tree seedlings. A total of 21 tree species were recorded in these quadrats, which was consistent with the composition of trees with ≥1 cm diameter at breast height. There was no sig-nificant interannual difference on species composition, but great variations among different seedling sub-plots. There were 11,959 tree seedlings recorded in three censuses, of which Fraxinus mandshurica and Tilia amurensis comprised of 72.75%. The seedling numbers of F. mandshurica, T. amurensis, and Pinus koraien-sis varied greatly among three censuses, while the numbers of other species varied little. Recruit seedlings of 15 species were recorded in three censuses, of which 10 species (T. amurensis, F. mandshurica, P. koraiensis and so on) were found every year. The numbers of recruit seedlings showed great interannual variations among different species and quadrats. Compared spatial distribution of tree seedlings with their seeds and large trees, we found that there were significant differences on individual numbers among different species. For T. amurensis, F. mandshurica, Acer mono, and A. pseudo-sieboldianum, their seeds and seedlings could be found in the entire 25-ha plot. For Ulmus japonica and Maackia amurensis, the distributions of their seed-lings were inconsistent with their seeds and large trees. For T. mandshurica and Malus baccata, with fewer seeds, seedlings, and large trees, the distributions of seedlings were consistent with these of their seeds and large trees.