以尾叶桉 (EucalyptusurophyllaS .T .Blake)自交F1子代、尾叶桉株间杂交F1子代、尾叶桉自由授粉F1子代和尾×巨桉 (E .urophylla×grandis)种间杂交F1子代林为试材 ,讨论分析了桉树生长、材性指标的近交退化和杂种优势规律性 .结果如下 :①尾叶桉近交退化现象呈现自交子代比自由授粉子代显著 ,生长性状比材质性状显著的规律性 .②尾叶按自交子代树高、胸径和材积具有显著至极显著的近交退化 ;生材含水率、木材基本密度和树皮厚度无近交退化 .③尾叶桉自由授粉子代树高、胸径和材积有一定程度的近交退化 ,但不甚显著 ;生材含水率、木材基本密度和树皮厚度无近交退化 .④尾叶桉与巨桉种间杂交子代的树高、胸径和材积可获得显著的杂种优势 ,但不同杂交组合的杂种优势率大有差别 ;子代的生材含水率、木材基本密度和成熟材纤维长度无杂种优势 ;子代的树皮厚度和 1%NaOH抽提物含量呈显著性降低 The F1 progeny of Eucalyptus urophylla S.T.Blake, F1 progenies of F1 hybrid between Eucalyptus urophylla, F1 hybrid of F1 pollination of E. urophylla and E.urophylla × grandis F1 progeny Lin as the test material to discuss and analyze the eucalyptus growth and wood properties inbreeding and heterosis regularity.The results are as follows: ① Eucalyptus tenuiflora inbred degeneration showed self-pollination than the free pollination progeny significantly, Growth traits than the material properties of significant regularity.②The height, DBH and volume of the selfing offspring had significant to very significant inbreeding degeneration; the moisture content of wood, the basic wood density and bark thickness had no inbred degeneration. ③ Eucalyptus urophylla free pollinated offspring tree height, DBH and volume have a certain degree of inbreeding degeneration, but not significant; raw material moisture content, wood basic density and bark thickness no inbreeding.④ Eucalyptus urophylla and giant The tree height, breast diameter and volume of the interspecific hybrid progeny of E. grandis could obtain significant heterosis, but the heterosis rates of different cross combinations differed significantly. The offspring’s moisture content, basic wood density and mature fiber length were all non-hybrid Advantages; offspring of bark thick NaOH and extract content of 1% was significantly decreased