Abstract: Studying the flowering development and seed germination of introduced Eucalyptu dunnii and mastering its reproductive growth law can provide a theoretical basis for seed garden.In this study,a blooming plant growing in Zitong County was selected as the experiment subject.The results were as follows:florescence date of Eucalyptu dunnii being from Mid and late February to mid and late October.Depending on morphologic change,flowering could be divided into 6 phases:Flower bud differentiation stage,inflorescence formation stage,opercle color change stage,opercle enlargement and shedding ring formation stage,flowering period,seed development stage.The development process of the buds on the same inflorescence was basically the same,and the growth of buds near the base of the same branch was faster than that of the top buds.The development of flower buds in different positions showed a random trend.Opercle had 3 to 4 ovary cavities,the number of shriveled seeds was far more than the number of effective seeds,and on a average,each capsule containing five normal seeds could develop into seedlings.