In order to determine and contrast the mode of action and cell toxicity mechanism of six botanical alkaloids(namely,harmaline,camptothecin, ricinine, matrine, macleay cordata and nicotine) against insect cell line,the apoptotic bodies, the inhibition of cell proliferation and the cell cycle phases were investigated by inverted phase contrast microscope, MTT test, and flow cytometry, respectively. The results showed that obvious apoptotic bodies appeared in Spodoptera litura cultured cell line SL-1 after 48~60 h treatments with harmaline at concentrations of 5.0 μg/mL and 20.0 μg/mL or camptothecin at concentrations of 0.5 μmol/L and 1.0 μmol/L.12~48 h after the same treatments, it showed obvious inhibition of cell proliferation and G2/M arrest of SL-1. It also showed that similar inhibitive effect on cell proliferation and G2/M arrest on SL-1 cell line after the treatments with macleay cordata alkaloid and ricinine at the concentrations of 5.0 μg/mL and 20.0 μg/mL respectively, but no obvious apoptosis induction. The only significant SL-1 cell line proliferation inhibition was got after the treatment with nicotine and matrine at the concentrations of 5.0 μg/mL and 20.0 μg/mL. These results provided some valuable information to the investigation of the diversity of activities of botanical alkaloids against insect pests and their cell toxicity mechanism.