Abstract: According to the results of observing and analyzing of gall and its host leaf structure of Rhus chinensis,it was found that the selectivity of Schlechtendalia chinensis on the position of host leaf was decided by the leaf structure of Rhus chinensis. The thickness of leaf-wings is 2. 3 times more than that of leaf-lets; the ratio of palisade tissue to spongy tissue was much different between them. There was only one fifth of leaf-wings to leaf-lets. The formation result of gall aphid on the leaf-wings was better than that on the leaf-lets. The horned gall hosted on the leaf-wings, with a thick gall-shell, is heavier than that on the leaf-lets. For these reasons, Rhus chinensis var. raxburghii with narrow and limited leaf-wings is unsuitable for plantation as a host tree. There was developed storage tissue and aerenchy- ma of horned gall; The shell thickness of the gall almost stopped growing one month later after the embryo gall has formed(in the middle of June) ,but the diameter and the volume of gall was going to increase in a high-speed until mature period (at the beginning of October).