Abstract:The inhibition of cell proliferation,cell morphological change and mitochondrial membrane potential change of ethanol extracts of 20 Thailand plants on Spodoptera litura (Sl-1) cell were investigated by MTT test,inverted phase contrast microscope and flow cytometry,respectively.The results showed that the Sl1 cell proliferation inhibition effect of 5 ethanol extracts including Thailand plants (Zingiber officinale Roscoe, Alpinia galangl (L.) Willd.,Azadirachta indica A.Juss var.siamensis Valeton,Curcuma longa Dennst and Citrus hystrix DC) was better than that of the control rotenone,and the inhibition was dosedependent. After 24 h of the treatment,cells showed obvious morphological changes,including adhesion capacity reduction,vacuole and debris appearance.After 48 h of the treatment,more and more vacuoles and debris were present obviously in the media.Moreover,these five ethanol extracts could induce cell mitochondrial membrane potential change,among which A. indica A. Juss-var. siamensis Valeton and C. hystrix DC were more effective.In conclusion,Z. officinale Roscoe,A. galangl (L.) Willd.,A. indica A. Juss var. siamensis Valeton,C. longa Dennst and C. hystrix DC possessed cytotoxicity on Sl-1 cells and deserved further researches.