Objective] In order to rapidly and precisely identify the excellent gene for the breeding of Eu-calyptus urophylla, the construction of core collection of E.urophylla was necessary .Establishing a core collection of E.urophylla could simplify the management and enhance the utilization of genetic resources in E.urophylla research programs.[Method] Based on 17 quantitative traits, height, diameter and vol-ume of 194 families from 27 provenances of E.urophylla, core collections were constructed using different sampling proportions ( 5%, 10%, 20%, 30%, and 40%) , 3 distances ( Euclidean distance , Standard-ized Euclidean distance , and Mahalanobis distance ) , 4 hierarchical clustering methods ( Single distance method, Complete distance method, Unweighted pair-group average method and Ward’s method), and 2 sampling strategies ( random sampling and least distance stepwise sampling ) were employed .The genetic variation of the quantitative traits among these core collections was compared by evaluating the mean difference percentage ( MD) , variance difference percentage ( VD) , changeable rate of coefficient of var-iation ( VR) and coincidence rate of range ( CR) of the traits.[Result and conclusion] The results showed that the primary core collection was constructed with 10%sampling proportion , standardized Eu-clidean distance , Single distance method , and least distance stepwise sampling , which was composed of 100 families from 27 provenances of E.urophylla and the best representative of total germplasm .%【目的】为了快速、准确地从丰富的尾叶桉Eucalyptus urophylla种质资源中鉴定出育种上迫切需要的优异基因，初步构建了尾叶桉核心种质，以便简化管理，提高遗传资源在尾叶桉改良中的利用效率。【方法】以尾叶桉27个种源194个家系的树高、胸径、材积等17个数量性状为依据，采用不同的取样比例（5％、10％、20％、30％和40％）、3种遗传距离计算方法（欧氏距离、标准欧氏距离和马氏距离）、4种系统聚类方法（最短距离法、最长距离法、不加权类平均法和离差平方和法）和2种取样方法（随机取样法和最小距离逐步取样法）构建尾叶桉核心种质资源库，利用均值差异百分率（MD）、方差差异百分率（VD）、变异系数变化率（VR）和极差符合率（CR）作为构建核心种质的评价指标。【结果和结论】结果表明采用10％的抽样比例、标准欧氏距离、最短距离系统聚类法和最小距离逐步取样法构建的包括25个种源100个家系的尾叶桉核心种质最能代表原有的种质群体。
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