The research has been carried out to optimize a recombinant S. cerevisine fermentation process for the production of an anticoagulant hirudin. The structural gene coding for hirudin was combined with the GAL10 promoter for controlled expression, the MFal signal sequence for hirudin secretion, and the GAL7 terminator for transcriptional termination. Growth medium composition and environmental conditions were optimized for maximizing cell growth and final hirudin concentration. The optimized conditions included yeast extract 40g/$ell$, casamino acid 5g/$ell$, g1ucose 20g/$ell$, galactose 30g/$ell$, DO 50% and temperature $30^{circ}C$. These conditions yielded the specific cell growth rate of $0.13hr^{-1}$, the final cell density of 30g cell/$ell$ and the final hirudin concentration of 64mg/$ell$ in the batch fermentation with a 2.5$ell$ jar fermentor.