OBJECTIVE： To study the anti-tumor effects of ethyl acetate part of Smilaz china on H22 liver cancer-bearing mice and its mechanism. METHODS： 90 mice were randomly divided into normal group， model group， positive control group （cytoxan， 0.02 g/kg， ip， every 2 days） and ethyl acetate part of S. china low-dose， medium-dose and high-dose groups [1.0， 2.0， 4.0 g（crude drug）/kg， ig， twice a day]. Except for normal group， H22 transplanted models of mice were established. The next day after modelation， treatment groups were given relevant medicine， and normal group and model group were given constant volume of 0.5％ sodium carboxymethylcellulose solution intragastrically. The change of body weight and tumor weight were observed after medication； the serum levels of VEGF and neoangiogenesis （NOS） were determined as well as vascular permeability of tumor； the expression of CD31 was detected in tumor tissue. RESULTS： Compared with model group， body weight and tumor weight of positive control group were decreased significantly， while the serum levels of VEGF and NOS， vascular permeability of tumor were increased significantly （P＜0.05 or P＜0.01）. Tumor weight and the expression of CD31 were decreased significantly in ethyl acetate part of S. china medium-dose and high-dose groups， while serum levels of VEGF and NOS， vascular permeability of tumor were increased significantly （P＜0.05 or P＜0.01）. Tumor weight were decreased significantly in ethyl acetate part of S. china low-dose group， while vascular permeability of tumor was strengthened （P＜0.05 or P＜0.01）. CONCLUSIONS： The ethyl acetate part of S. china shows anti-tumor effects in H22 liver cancer-bearing mice， and its mechanism might be associated with reducing the serum levels of VEGF and NOS， improving vascular permeability of tumor and inhibiting neovascularization.