Objective:　To　investigate　the　effect　of　high　expression　of　TET1　catalytic　domain　(TET1-CD)　gene　on　the　proliferation　and　migration　of　breast　cancer　MDA-MB-231　cells　and　its　underlying　mechanism.　Methods:　MDA-MB-231　cell　line　with　high　TET1-CD　expression　was　established　by　lentiviral　transfection.　Real-time　quantitative　PCR　was　used　to　detect　the　mRNA　expression　of　TET1-CD.　Transwell　assay　and　cell　scratch　assay　were　used　to　detect　cell　migration　ability,　MTT　assay　and　colony　formation　assay　were　used　to　detect　cell　proliferation　capacity.　And　WB　was　adopted　to　detect　the　expressions　of　EMT-related　proteins　(E-cadherin,　Vimentin,　MMP2)　and　Wnt,　Hedgehog　pathway-related　proteins　in　MDA-MB-231　cells.　Results:　The　MDA-MB-231　cell　line　with　high　TET1-CD　expression　was　successfully　constructed　(all　P＜0.01).　TET1-CD　over-expression　significantly　inhibited　the　proliferation　and　migration　of　breast　cancer　MDA-MB-231　cells　(P＜0.01);　in　addition,　TET1-CD　over-expression　increased　the　expression　of　E-cadherin,　but　down-regulated　the　expressions　of　Vimentin,　MMP2,　β-catenin,　Gli1,　C-myc　and　CyclinD1　(all　P＜0.05).　Conclusion:　TET1-CD　may　inhibit　the　proliferation　and　migration　of　breast　cancer　MDA-MB-231　cells　by　inhibiting　the　EMT　through　Wnt　and　HH　signaling　pathway.　©　2019,　Editorial　office　of　Chinese　Journal　of　Cancer　Biotherapy.　All　rights　reserved.