Abstract: Glucose metabolism plays a very important role in fruit quality.It is mainly governed by carbohydrate metabolism and the related enzyme activities.And,leaf photosynthesis and fruit development are closely related with starch catabolism.The amylase activities in Poon-kan and Macrott oranges after mixed grafting were monitored for this study.The results showed that the amylase activity of Macrott was higher than that of Poon-kan in general.At the same time,the amylase activity of Poon-kan was enhanced after the mixed grafting.The activity changes of the two orange varieties tended to be similar.