Abstract: The effects of bagging on sugar contents and related enzyme activities in sorbitol metabolism were studied with ‘Red Fuji’ apple fruits. The results showed that the contents of sucrose, glucose and fructose and SDH activity in bagging fruits almost had the same change tendency as those of control fruits during the whole developmental period. Compared with control, the contents of sucrose, glucose and fructose in bagging fruits was much lower in some extents, however, the contents of sorbitol increased significantly. The results also indicated that fruit bagging greatly decreased SDH activity, but increased SOX activity during the late development period. The results of correlation and linear analysis also showed that the accumulation of fructose had significant correlation with SDH activity. It is concluded that fruit bagging influenced the sugar accumulation through reducing sorbitol metabolism in apple fruit.