OBJECTIVE To investigate the inhibitory effect and mechanism of Modified qifang weitong granules on gastric cancer based on in vitro and in vivo experiments. METHODS Human gastric cancer HGC-27 cells were divided into the following groups: control group （treated with fetal bovine serum）， 10% drug-containing serum group， 15% drug-containing serum group， 20% drug-containing serum group， and 5-fluorouracil （5-Fu） group （positive control， 3.90 μg/mL）. After culturing the cells in each group with the corresponding serum/drug solution， their proliferation， migratory and invasive abilities， as well as the cell cycle， were assessed. Additionally， the expression levels of epithelial-mesenchymal transition （EMT）-related proteins [E-cadherin， N-cadherin， and vimentin] in the cells were measured. Logarithmic-phase HGC-27 cells were harvested and subcutaneously injected into the right axillary region of nude mice to establish a subcutaneous xenograft tumor model in nude mice. The successfully modeled tumor-bearing nude mice were randomly divided into model group， low-， medium- and high-dose groups of Modified qifang weitong granules （17.65， 35.29 and 70.58 g/kg， respectively）， and 5-Fu group （25 mg/kg）， with 5 mice in each group. After 14 days of treatment with the corresponding drugs in each group， the histopathological morphology of the tumor tissues in the nude mice was observed. Immunohistochemistry and Western blot assay were employed to detect the expression levels of EMT- related proteins in the tumor tissues of the nude mice. RESULTS In the cell experiment， compared with the control group， the cell proliferation rate， migration rate， number of invasive cells， as well as the expression levels of N-cadherin and vimentin proteins， and the percentage of cells in the G2/M phase were all significantly decreased/reduced in the 15% drug-containing serum group， 20% drug-containing serum group （P＜0.05）. Conversely， the percentage of cells in the G0/G1 phase and the expression level of E- cadherin protein were significantly increased （P＜0.05）. In animal experiment， compared with the model group， the high-dose group of Modified qifang weitong granules exhibited significantly reduced tumor mass and expression levels of N-cadherin and vimentin proteins in the tumor tissues of nude mice （P＜0.05）， while the expression level of E-cadherinprotein in the tumor tissues was significantly increased （P＜0.05）. Additionally， the tumor cells varied in size and showed extensive necrosis. CONCLUSIONS Modified qifang weitong granules effectively inhibit gastric cancer in both in vitro and in vivo models， and the mechanism of action is related to the suppression of EMT.