Abstract: To study the biosynthesis gene cluster of the polysaccharide produced by marine bacterium Pseudoalteromonas issachenkonii HZ,and to clone the gene which plays a key role in the synthesis of polysaccharide.Glycosyltransferase gene was amplified by designing primers using PCR technology from marine bacteria Pseudoalteromonas issachenkonii HZ,and examined the effect of temperature,p H and salt concentration of glycosyltransferase gene expression by real- time fluorescence quantitative PCR.The results showed that the low temperature was in favor of the expression of the glycosyltransferase. With the increase of the temperature,the expression of the gene of the glycosyltransferase increased first and then decreased. It was showed that glycosyltransferase gene expression level increased rapidly,and the glycosyltransferase gene expression level of Pseudoalteromonas issachenkonii HZ grown at 15 and 35 ℃ were 5.2,5.8 times higher than grown at 20 ℃,respectively.4.5% salt concentration could increase the expression level of glycosyltransferase gene 2.5 times compared to that of 3.5% salt concentration,while 5.5% salt concentration glycosyltransferase gene expression level was 2 times compared to 3.5% salt concentration. The glycosyltransferase gene expression level of Pseudoalteromonas issachenkonii HZ grown at p H8 and 9 were 1.64、1.67 times higher than grown at p H7,respectively.The research on glycosyltransferase gene of Pseudoalteromonas issachenkonii HZ laid a foundation for exploring the mechanism of adaptation to the environment.