The characteristics of one Candida tropicalis yeast strain which can produce ethanol from xylose-fermenting was studied under different fermentation conditions.The results showed that dissolved oxygen concentration had a great influence on both the yield and productivity of ethanol,with moderate dissolved oxygen concentration being conducive to cell growth and ethanol accumulation.A higher initial cell concentration and urea are conducive to the yield of ethanol.In the condition of sufficient carbon and nitrogen source,extending the fermentation time,yield of ethanol can reach up to the steady-state of 25.58 g/L while the cell concentration tends to be stable,about 6.54×108/mL.The steady state is a dynamic balance due to the equivalent of ethanol production and consumption.