Very high gravity（VHG)fermentation and using self-flocculating yeast are both advanced technologies to reduce the energy cost in fuel ethanol industry.Oxidoreduction potential（ORP)reflecting yeast momentary physiological status can be regulated for improving cell performance under severe stresses in VHG condition.Batch fermentations with initial glucose concentrations of 200 g·L-1

250 g·L-1 and 300 g·L-1

ORP setting values of -100 mV

-150 mV and no control

were undertaken to evaluate the effects of ORP and initial glucose on ethanol production.It was shown that biomass and viability under ORP control were higher than no control

which resulted in higher net ethanol accumulation and productivity.Moreover

since absence and excess of oxygen supply decreased yield

the best ORP level was found at -150 mV in 300 g·L-1 initial glucose fermentation.ORP control had influence on flocculation as well.By using a multiple variables linear fitting approach

ORP seemed to have a positive correlation with size distribution though its effect is not direct.