Abstract: This paper reports the result of works on 5 plots of the seasonal rainforest at Manyanguang,Damenglong in Xishuangbanna in 1987-1988.The insect specimens were collected in dry (January,May) and rainy (August) seasons.Major research is based on numbers of individuals,species,genera and families to study the diversity,evenness and dominance of the communities and the seasonal changes of populations of hemipterous insects.1.In the different plots of the level structure of seasonal rainforest,the species,gendera,families,individuals and diversity index of hemipterous insects in the plots E,S,W,N of forest edge more than insects in plot O of the ecntre forest.The forest marginal effect was quite clear.2.Making a comparison among numbers of individuals,species,genera,families and diversity index of insects in different layers of 5 plots of the vertical structure of seasonal rainforest,the most number was in middle layer,especially in the crisscross space where high of the herb layer and young scrab layer were 1.5-2 m,the species and amount of the insects were the most and the aboundantest.