Abstract: The changes of the volatile acid was investigated under conditions of different original sugar content and adding amounts of SO 2 during the fermentation process of red icewine. The result showed that under the same amount of SO 2 the higher was original sugar content of grape juice, the higher was volatile acid during the fermentation process of red icewine. Under the same original sugar content of the grape, when SO 2 dosage was between 30～100mg /L, the volatile acid decreased with SO 2 dosage increasing.When SO 2 dosage was 150mg /L, its volatile acid was higher than the dosage of 30mg /L . Volatile acid generation and accumulation was obviously influenced by original sugar content of grape juice and adding amount of SO 2 during the fermentation process of red icewine.