Abstract: Plant sexual system affects ecosystem composition and population evolution, and also it is affected by multiple ecological factors. In order to analyze the correlations between the sexual system distribution and the ecology of woody plants in Changbai Mountain of northeastern China, 206 species of woody plants at different altitudes in Changbai Mountain were investigated, and their floral characteristics, fruit type, life-form and pollination characteristics were observed and recorded in detail. Correlations between the above characteristics and the plant sexual system were analyzed by chi-square test and multivariate logistic regression. The sexual system composition of the woody plants and other plant communities in Changbai Mountain were compared. Factors affecting the sexual system composition and reproduction strategies of the woody plants were also investigated. The results showed that the sexual system of woody plants in Changbai Mountain was composed of hermaphrodite plants(51.9%), monoecious plants(18.5%) and dioecious plants (29.6%). With the increase of altitude, the proportion of monoecious plants and dioecious plants increased, and the proportion of hermaphrodites was higher than temperate forests in North America. Hermaphrodite was strongly associated with shrubs, showing floral display, white flowers, zygomorphic, specialist entomophily and fleshy fruits. Monoecious and dioecious were strongly associated with trees, inflorescence, yellow-green, actinomorphic, generalist entomophily and anemophily and dry fruits. In conclusion, the sexual system of woody plants on Changbai Mountains is connected with phylogeny, and shows the coevolutionary relationship with insect diversity.