Abstract: In order to improve the yield of erythritol, the original strain osmotolerant yeast T-3-2 was treated by UV and HNO2, and its fermentation condition was optimized by single factor and response surface methodology (RSM) .A high and stable yield mutant named UN-11 was obtained.The erythritol yield of UN-11 was 78.3mg/mL, which increased 38.8% compared with the original strain.The second-order polynomial equation for erythritol yield was established by response surface analysis theory.Optimized processing conditions obtained were fermentation temperature of 31℃, rotate speed of 170r/min and inoculation amount of 9.8% (v/v) .Under these optimized conditions, the predicted yield of fitted model was 84.93mg/mL and verifying test result was 85.25mg/mL.The model had some guiding sense for erythritol industrial production.