Sugars are major constituents in many food systems. In this study, we tried to establish a rapid identification method to detect irradiated food which contained sugars by analyzing ultraweak luminescence of the food. The results indicated that the ultraweak luminescence behavior of glucose and sucrose changed greatly after gamma ray irradiation. Under dry condition, there were little changes in ultra luminescence intensities with the irradiated samples of glucose and sucrose, however, they did show marked changes in their ultra luminescence intensities when water was added during the measurement. It seemed that photon numbers of luminescence peak could be correlated to the dose delivered to the samples. The difference in the luminescence behavior of glucose and sucrose may provide an effective way to differentiate irradiated food.