Candida magnoliae is one of osmophilic yeasts and can produce erythritol.This research focused on the best carbon source,the best nitrogen source,the best ratio of carbon to nitrogen and the effect of NaCl and KCl to study the effect of osmotic pressure on the production of erythritol through fermentation.The results indicateed that glucose and yeast extract were the best carbon resource and nitrogen resource respectively.The best ratio of carbon to nitrogen was 20:1.Under such conditions,the conversion efficiency of erythritol reached 14.2%.After addition of various concentration of KCl or NaCl into the medium,we found that the cell growth rate was decreased with the increasing concentration of KCl or NaCl.The highest yield of erythritol was obtained at 0.4mol/L KCl or 0.3mol/L NaCl,which were 18.4g/L and 17.4g/L respectively.If the concentration of salt was expressed by osmotic pressure,the yield of erythritol decreased as the osmotic pressure increased.The high osmotic pressure inhibited the cell growth.