[Objectives]  To ascertain the effect of n-butyl alcohol extracts of Momordica charantia leaves on the growing, development and fecundity of Ostrinina furnacalis (Güenée). [Methods]  The effects of n-butyl alcohol extracts of M. charantia leaves on the survival rate and the developmental duration of O. furnacalis larvae and the fecundity of O. furnacalis adult females were investigated by adding these extracts to the food provided to O. furnacalis larvae and adult females under laboratory conditions. [Results]  The results demonstrated that after treating the survival rate of second instar respectively. In addition, developmental duration of treated larvae was significantly longer than that of the control group, and the rates of fecundity inhibition were 12.63%, 22.74% and 37.27%, respectively. Extracts of M. charantia leaves had an apparent inhibitory effect on Spodoptera litura cell proliferation, cellular morphology and growth density; cells shrunk, cellular nuclei migrated and even disappeared and cytoplasm leaked out after treatment. The IC₅₀ values were 180.96, 158.54 and 122.87 mg/mL at 24, 48 and 72 h after treatment, respectively. The growth density of cells decreased significantly compared with control cells, after 6-72 h of exposure with increasing concentration and the treatment time. Treating cells with 125 mg/mL n-butyl alcohol extracts of M. charantia leaves for 2, 3, 4 and 5 days inhibited glucose absorption by 7.66, 13.97, 19.45 and 27.30%, respectively. [Conclusion]  These results suggest that the n-butyl alcohol extracts of M. charantia leaves are strongly cytotoxic to Spodoptera litura cells, which may account for the observed decline in female fecundity of O. furnacalis.