Through　research　in　literature,　homologous　alignment　and　phylogenetic　analysis,　gntI　from　Micromonospora　purpurea　and　sisI　from　Micromonospora　inyoensis　were　presumed　to　be　3′,　4′　-double　dehydroxylase　gene.　Then　the　nucleic　acid　sequence　of　gntI　and　sisI　were　amplified　and　ligated　to　expression　vector　pET30　for　heterologous　expression　in　E.　coli　BL21.　Bioinformatics　was　utilized　to　analyze　the　hydropathy　plot　,　structure　and　catalytic　domain　of　the　protein　GntI　and　SisI.　Based　on　homologous　modeling,　the　spatial　structures　were　gained,　speculating　that　α-helix　was　the　main　secondary　structure,　and　catalytic　domain　may　be　located　at　40-60,　100-120　amino　acids.　This　study　established　the　foundation　for　further　functional　research　and　potential　application　of　3′,4′　-double　dehydroxylase.