To Investigate the inhibition effect of steamed Panax notoginseng on Lewis lung cancer, and find out whether there is a effect-enhancing and toxicity-reducing effect when use in combination with paclitaxel or pemetrexed disodium. Methods: C57BL/6 mice inoculated with Lewis lung cancer were randomly divided into model group, positive group, raw Panax notoginseng low, medium and high dose group, steamed Panax notoginseng low, medium and high dose group(each group n=13～14). Among them, raw and steamed Panax notoginseng groups received intragastric administration according to low, middle, high dose(585 mg·kg-1, 1170 mg·kg-1, 2340 mg·kg-1), positive group mice received intraperitoneal injection of CTX(60 mg·kg-1) on the first day. After the trial, calculated inhibition rate against tumor and recorded body weight before/after administration, body weight ratio(FBW/IBW) and death. Then the new Lewis lung cancer inoculated C57BL/6 mice were randomly divided into 9 groups (n=10), model group (0.5% CMC-Na solution), steamed Panax notoginseng group, raw Panax notoginseng group, paclitaxel group, steamed Panax notoginseng plus paclitaxel group, raw Panax notoginseng plus paclitaxel group, ALIMTA group, steamed Panax notoginseng plus ALIMTA group and raw Panax notoginseng plus ALIMTA group. Steamed and raw Panax notoginseng were continuously intragastric administrated at the dose of 1170 mg·kg-1, and paclitaxel(15 d, 10 mg·kg-1), ALIMTA (120.3 mg·kg-1) were intraperitoneal injected since Day 1(every three days, 3 times in total). After the trial, calculated inhibition rate against tumor, determined peripheral hemogram and recorded body weight before/after administration, body weight ratio(FBW/IBW) and death. Results: Compared with the model group, steamed Panax notoginseng(1170 mg·kg-1) showed significantl inhibition rate(41%, P<0.01); raw Panax notoginseng(2340 mg·kg-1) also showed significantl inhibition rate(P<0.05), but with no clinical significance, and had several adverse reactions. Steamed and raw Panax notoginseng improved the inhibition rate of paclitaxel and ALIMTA; Steamed Panax notoginseng seemed to reduce the toxicity of paclitaxel, whereas raw Panax notoginseng increased the toxicity of chemotherapy drugs. Conclusion: Steamed Panax notoginseng significantly inhibit the growth of Lewis lung cancer; and when use in combination with chemotherapy drugs, could improve the inhibition rate, meanwhile, reduce the toxicity of chemotherapy drugs. There is no clinical significance of antitumor effect of raw Panax notoginseng; although raw Panax notoginseng could also improve the inhibition rate of chemotherapy drugs, but exhibit obvious adverse reactions.