Abstract: The concentration of some contents in the leaves of Rhus chinensis has a great variation range due to the different breaking period of host tree. These contents including soluble sugar, tannin acid and vitamin C are relevant to the order number of the leaves. The earlier breaking leaves have much more contents than that of the later. But the concentration of amino acid has less relation to the order number of leaves. A serial investigation and analysis showed that the host leaves with higher concentration of nitrogen are much more resistible to the gall aphid than the lower. And the concentration of nitrogen of host tree’s leaves has a close relation to the soil. For these evidences, the concentration of nitrogen of host tree’s leaves can be regulated by selection the condition of soil and application of fertilizer. The susceptibility or resistance of host tree to gall aphid can be controlled to some extent. Consequently, it could be supposed that a new way to improve the yield of horn gall is actable by means of regulation the susceptibility or resistance of Rhus chinensis to Schlechtendalia chinensis .