【目的】 草地贪夜蛾Spodoptera frugiperda是新入侵我国的迁飞性害虫，为了筛选出有效和不易受损的形态鉴别特征。【方法】 本研究运用比较形态学和外生殖器解剖技术，筛选稳定、可靠的外部形态特征，描述雌雄外生殖器特征。【结果】 草地贪夜蛾的大小等21个外形特征在不同个体间存在差异，不适合用于草地贪夜蛾的准确鉴定。新筛选的翅基部黑斑等4个前翅特征，下唇须节黑色横带、前足胫节密被长鳞片、前足跗节黑色、腹部腹面黑斑、肩板颜色均一、前足基节内侧长毛6个非翅面外形特征在草地贪夜蛾个体间稳定，其中前翅中部倾斜的椭圆环形斑等4个特征、颜色均一肩板等5个特征、环形斑内部颜色特征分别存在于草地贪夜蛾雌雄蛾、雄蛾和雌蛾中。新筛选的外形特征可分别用于准确区别草地贪夜蛾与斜纹夜蛾、甜菜夜蛾。新描述了阳茎基环长大于宽等6个雄性外生殖器特征和囊导管基部明显宽于端部等4个雌性交配囊特征，其中3个雄性外生殖器特征和3个雌性交配囊特征可分别用于准确鉴定草地贪夜蛾和斜纹夜蛾雄蛾、草地贪夜蛾雌蛾和甜菜夜蛾雌蛾。【结论】 本研究结果不仅为草地贪夜蛾雄蛾鉴定提供了新的前翅特征，还首次为雄蛾鉴定提供了非翅面特征和为雌蛾鉴定提供了前翅特征，也筛选了新的雄性外生殖器特征和雌性交配囊特征，对我国夜蛾科昆虫生殖器研究有一定的参考价值。

[Objectives]  To describe morphological characteristics that can be used to accurately identify the moth Spodoptera frugiperda, an invasive pest that has recently become established in China. [Methods]  Stable, diagnostic, morphological characteristics of male and female moths, including male genitalia and female bursa copulatrix are described. [Results]  Body size and other 20 morphological characteristics are too variable among individuals to be used to accurately identify S. frugiperda. In addition to 4 forewing characteristics, including black spots on the base of the forewing, 6 other morphological features, such as black scale bands on the labial palp, are found to be sufficiently invariant among individuals to serve as diagnostic features. An oblique orbicular spot in the middle of the forewing, and other 3 morphological characteristics are confined to males and females. The uniform color of humeral plates and 4 other features are confined to males, whereas the characteristic “same color of the inner part to the forewings” is confined to females. Four and two newly identified external morphological features accurately distinguish S. frugiperda from S. litura and S. exigua moths, respectively. Newly identified 6 diagnostic features of male S. frugiperda genitalia include juxta longer than wide, whereas newly identified 4 features of females bursa copulatrix include the base of the ductus bursae being obviously wider than the end. Three features of the male genitalia, and 3 of the female bursa copulatrix, accurately distinguish S. frugiperda from male S. litura and female S. exigua, respectively. [Conclusion]  The results of this study not only provide morphological characteristics of the forewing but also additional morphological characteristics of other body part that allow the accurate identification of male S. frugiperda. Forewing features that allow the accurate identification of females are also provided for the first time. In addition, our results provide a useful reference on the genitalia of noctuids, including some newly described features of the male genitalia and female bursa copulatrix.