Abstract: Through research in literature,homologous alignment and phylogenetic analysis,gntI from Micro- monospora 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.