〔Abstract〕 Objective To investigate the effect of tumor suppressor gene programmedcelldeath 4(PDCD4) expression level on inhibition of human gastric cancer xenograft growth in nude mice byCelastrus Orbiculatusextract(COE). Methods The exogenous recombinant eukaryotic plasmid pcDNA3.1-PDCD4 was transfected into human gastric cancer cell line SGC-7901, after screened by G418, a stable transfected cell line with high expression of PDCD4 was established. The subcutaneously transplant tumor model of human gastric cancer in nude mice was established and randomly divided into the control group, pcDNA3.1 group, pcDNA3.1-PDCD4 group, COE group, pcDNA3.1+COE group, and pcDNA3.1-PDCD4+COE group. The growth status and tumorigenic incubation period of xenograft were monitored, and protein expression level of PDCD4、E-cadherin、N-cdherin and Vimentin in xenograft was detected by immunohistochemistry assay. Results Compared with the control group, the tumor inhibition rates of pcDNA3.1-PDCD4 group, COE group, pcDNA3.1+COE group, pcDNA3.1-PDCD4+COE group were 59.29%, 57.52%, 58.41%, 71.68%, respectively. The protein expression level of PDCD4, E-cadherin was significantly up-regulated, while the protein expression level of N-cadherin, Vimentin significantly decreased. In pcDNA3.1-PDCD4+COE group, the tumor inhibition rate and the changes of PDCD4、E-cadherin、N-cdherin and Vimentin protein expression levels were significant higher than other groups(P<0.01). Conclusion The tumor suppressor gene PDCD4 may be involved in the inhibitory effect of COE on the growth of human gastric carcinoma xenograft tumor in nude mice, and its mechanism may be related to the influence of EMT process.