Abstract: When pentoses and hexoses present in spent sulfite liquor (SSL) were simultaneously fermented to ethanol by a Candida shehatae strain, the no-sugar reducing substrates and acetic acid were also consumed, resulting in a pH change profile in which pH was downward in the early stage and upward in the late stage. The repression of hexose catabolite on pentose fermentation could be resolved by controlling the amount of air supply. The best conditions of fermentation were also studied. SSL contaning 19. 94 % solids was neutralized to pH 5. 00～5. 50 followed by fermentation at 38±1℃ for　34 h. With dissolved oxygen concentration at a range of 0. 9～ 1. 0 mg· L~-1. Sugar consumption was 89. 9 %, ethanol yield was 0. 40 g ethanol per g sugar consumed, which is 83. 1 % of the theoretical yield.