为揭示不同无性系杉木〔Cunninghamia lanceolata (Lamb.) Hook.〕鲜枝叶精油得率及抑菌活性的变异特征并筛选出优良无性系，以广东杉木第3代育种园中88个核心无性系为研究对象，比较分析了不同杉木无性系鲜枝叶精油的得率及其对大肠杆菌（Escherichia coli）和金黄色葡萄球菌（Staphylococcus aureus）抑制率的季节差异，采用群体均值四分法进行优良无性系筛选，并对筛选结果进行主成分分析验证，对精油得率与抑菌率进行Pearson相关性分析。结果表明：各季节的精油得率及精油对大肠杆菌和金黄色葡萄球菌抑制率的变异系数分别为30.68%～41.20%、41.73%～102.64%、113.80%～299.96%，在不同无性系间差异极显著（P<0.01），重复力均高于0.7，且多在0.9以上。夏季精油得率最高，但与其他季节的差异并不显著；夏季精油对大肠杆菌和金黄色葡萄球菌的抑制率均最高，并且，夏季精油对大肠杆菌的抑制率显著（P<0.05）高于春季和冬季，对金黄色葡萄球菌的抑制率显著高于秋季和冬季。基于精油得率及精油对大肠杆菌和金黄色葡萄球菌的抑制率，在春、夏、秋、冬季分别筛选出15、9、11、8个优良无性系，其中，无性系cx79在4个季节均表现优异。相关性分析结果显示：精油得率与抑菌率的相关系数存在明显的季节差异，其中，春季精油得率与抑菌率的相关性最强。综合分析认为，供试杉木核心无性系的鲜枝叶精油得率及抑菌活性变异较大，总体上存在明显的季节性差异和无性系间差异；cx79为最优无性系，可作为杉木精油应用及专用型品种的优良候选材料。

 To reveal the variation characteristics of yield and antibacterial activity of essential oil from fresh branches and leaves of different Cunninghamia lanceolata (Lamb.) Hook. clones and screen superior clones, 88 core clones from the third-generation breeding garden of C. lanceolata in Guangdong were taken as research objects, the seasonal differences in yield of essential oil from fresh branches and leaves of different C. lanceolata clones and its inhibition rates against Escherichia coli and Staphylococcus aureus were compared and analyzed, the superior clones  were screened by using the population mean quadrat method, the screening results were validated by using principal component analysis, and Pearson correlation analysis was conducted between yield and inhibition rate of essential oil. The results show that the coefficients of variation of yield of essential oil and inhibition rates of essential oil against E. coli and S. aureus in each season are 30.68%-41.20%, 41.73%-102.64%, and 113.80%-299.96%, respectively. There are extremely significant differences (P<0.01) among  clones, with repeatability values all greater than 0.7, mostly above 0.9. The yield of essential oil is the highest in summer, but the difference is not significant compared with the other seasons. While the inhibition rates of essential oil against  E. coli and S. aureus are both the highest in summer. In addition, the inhibition rate of essential oil against E. coli in summer is significantly (P<0.05) higher than those in spring and winter, and that against S. aureus is significantly higher than those in autumn and winter. Based on yield of essential oil and inhibition rates of essential oil against E. coli and S. aureus, 15, 9, 11, and 8 superior clones are screened in spring, summer, autumn, and winter, respectively, among which, clone cx79 exhibits excellent performance in the four seasons. The correlation analysis result reveals that there are striking seasonal variations in correlation coefficients between yield and antibacterial rate of essential oil, among which, the correlation between yield and antibacterial rate of essential oil in spring is the strongest. The comprehensive analysis indicates that the variations of yield and antibacterial activity of essential oil from fresh branches and leaves of test C. lanceolata core clones are relatively large, and there are pronounced seasonal and clonal differences in general. cx79 is identified as the optimal clone. It represents  an excellent candidate material for essential oil application and specialized cultivar development of C. lanceolata.