Abstract: Fresh orange juice were processed by ultra high pressure (UHP) and thermal treatments respectively, and their qualities were compared by relational evaluation. Both the two processing ways led to the loss of main components in orange juice to different degrees. However, the effect of main constituents on fresh orange juice processed by UHP was better than that by thermal treatment and less influence of UHP was observed on the color of fresh orange juice. After processed, the relative contents of ester, alcohols and ketones in orange juice slightly decreased. The relative contents of aldehydes in both processing orange juice was more than four times higher than that in fresh orange juice. The relative contents of hydrocarbons and other aroma components in orange juice also decreased.