Abstract: Glutathione(GSH) is one of the thiol short peptides,which widely exists in cells.It attracts attention because of its important physiological activity.We strengthen the cysteine synthesis to improve the GSH synthesis in Escherichia coli.The key enzymes,3-glyceric acid phosphate dehydrogenase(PGDH) and serine acetyltransferase,were overexpressed in E. coli MG1655 and then the GSH synthetase gshFas was co-overexpressed with the two enzymes.The results of fermentation in the flasks with the recombinant strains showed that the growth was decreased in the recombinants and the production of GSH reached 0.97 mmol/L,which was 1.56 fold that of original.The level of GSH biosynthesis can be improved significantly by increasing the supply of precursor cysteine.