A flavonoid 3'-hydroxylase from tea plant was engineered to synthesize B-3',4'-dihydroxylated flavones such as eriodictyol, dihydroquercetin and quercetin.Four articifical P450 constructs harboring both flavonoid 3'-hydroxylase gene from Camellia sinensis (CsF3'H) and P450 reductase gene from Arabidopsis thaliana (ATR1 or ATR2) were introduced into Escherichia coli strains TOP10, DH5α and BL21, resultantly engineering strains S1 to S12. The plasmid pYES-Dest52-CsF3'H harboring CsF3'H gene was introduced into yeast Saccharomyces cerevisiae WAT11 designated as strain S13. The plasmid pES-HIS-CsF3H::AtFLS 9 AA was constructed through fusing flavanone 3-hydroxylase gene from Camellia sinensis (CsF3H) and flavonol synthase gene from Arabidopsis thaliana (AtFLS). Plasmid pES-URA-CsF3'H and pES-HIS-CsF3H::AtFLS 9 AA were then co-introduced into yeast S. cerevisiae WAT11 designated as strain S14.Strain S6 generated highest bioconversion efficiency at 25℃ among all E. coli strains during 24 h fernentation. Supplemented with 1000 μmol/L naringenin, dihydrokaempferol and kaempferol, the maximum amounts of eriodictyol, dihydroquercetin and quercetin produced by strain S13 were 734.32 μmol/L, 446.07 μmol/L and 594.64 μmol/L respectively. Supplemented with 5 mmol/L naringenin, the maximum amounts of eriodictyol, kaempferol, quercetin, dihydroquercetin and dihydrokaempferol produced by strain S14 were 1412.16 μmol/L, 490.25 μmol/L, 445.75 μmol/L, 66.75 μmol/L and 73.50 μmol/L during 36-48 h fermentaion respectively.CsF3'H was engineered for biosynthesis of B-3',4'-dihydroxylated flavone.