Abstract: Objective To study the expression level of the hypoxia inducible factor-1α（HIF-1α）、zinc finger transcription factor Snail and E-cadherin in different hypoxia condition in the colorectal cancer SW480 cells,and to explore their effect on the proliferation,apoptosis,invasion and transference,approach the roles and mechanisms of them three in the hypoxia and epithelial-mesenchymal transition of colorectal cancer. Methods Chemical was used to induce the cell hypoxia model by cobalt chloride(CoCl₂),and three groups:normoxia group,hypoxia group and non-oxygen group were involved in this study.Methyl thiazolyl tetrazolium(MTT) method was used to detect the proliferative of colorectal cancer SW480 cells,extraorgan invasion experiment(Transwell method) was applied to evaluate the invasion and transference capability of cells,the cell cycle and apoptosis was examined by flow cytometry (FCM),the mRNA and protein expression levels of HIF-1α,Snail and E-cadherin were detected by real time PCR(RT-PCR) and Western blot. Results MTT disclosed that the proliferative activity of the colorectal cancer SW480 cells was increased gradually following the concentration increase of the cobalt chloride(P<0.05);transwell showed that the cells permeated the matrix membrane and polycarbonate membrane was increased gradually accompanied with the degree of hypoxia(P<0.05);FCM revealed that in hypoxia group and non-oxygen group,the cells in G₀/G₁ period was decreased obviously,the cells in G₂/S period was increased obviously,the cells apoptosis was degrade(P<0.05) compared with normoxia group;RT-PCR and Western blot displayed that hypoxia group and non-oxygen group compared with normoxia group,the mRNA and protein level of HIF-1α and Snail in SW480 cells was increased,the mRNA and protein of E-cadherin was decreased(P<0.05),furthermore,HIF-1α and Snail had positive correlation,and they had negative correlation with E-cadherin conspicuously(P<0.05). Conclusion The hypoxia and HIF-1α can promote the extraorgan proliferation activity of the colorectal cancer SW480 cells,inhibit its apoptosis and enhance its extraorgan invasion and migration.The possible mechanism is that hypoxia induced HIF-1α affect SW480 directly,or the hypoxia and HIF-1α expression promote Snail expression and inhibit E-cadherin expression,which lead to EMT and take it place.