Abstract: This Paper presents the contents of foliar nutrients and their seasonal variations for 9 major tree species in northeast China during a growing season.Using the Principal Component Analysis and Cluster Analysis,this paper demonstrated that N, P and Ca are importantly critical elements for plants, and Fe and Mn highly accumulated in the soil. Moreover, N, P and Ca, taken by plants are highly dependent on the soil contents of the elements, while uptake of Fe and Mn, is independent of the soil contents and is selective. From the nutrient utilization point of view, Pinus Koraiensis + Juglans mandshurica,Larix gmelini + Fraxinus mandshurica,hard broad-leaved tree + soft broad-leaved tree, conifer + broadleaf tree, and Betula platyphylla + other tree species are the rational mixed types in the establishment of mixed forests.