In　order　to　understand　condensation　heat　transfer　and　pressure　drop　characteristics　of　a　new　environment-friendly　refrigerant　R1234ze(E)　in　a　mini-channel,　the　VOF　(Volume　of　Fluid)　model　was　adopted　to　investigate　the　condensation　performance　of　R1234ze(E)　and　R134a　(Tsat=40　)　inside　a　mini-channel　(Dh=1　mm).　The　effects　of　mass　flux,　vapor　quality　and　physical　properties　on　condensation　heat　transfer　coefficients　and　pressure　gradients　were　discussed.　The　results　indicate　that　both　the　heat　transfer　coefficients　and　pressure　gradients　of　R1234ze(E)　and　R134a　increase　with　the　vapor　quality　and　mass　velocity.　The　condensation　heat　transfer　coefficients　of　R1234ze(E)　were　lower　than　that　of　R134a　under　same　conditions.　However,　the　pressure　gradients　of　R1234ze(E)　were　larger　than　that　of　R134a.　The　average　film　thickness　of　R1234ze(E)　was　on　average　15.7%　thinner　than　that　of　R134a.　The　effective　thermal　conductivity　played　an　important　role　in　local　heat　transfer　performance　of　the　two　refrigerants.　The　local　film　distribution　of　R1234ze(E)　was　similar　with　that　of　R134a.　The　existing　correlations　seemed　to　underestimate　the　pressure　gradients　of　R1234ze(E)　with　mean　absolute　deviation　of　30%.　©　2020,　Editorial　Board　of　＇Journal　of　Chemical　Engineering　of　Chinese　Universities＇.　All　right　reserved.