The relationships between fruit granulation and low temperature in winter of different years in Zigui County of Three Gorges Reservoir Area were studied. The changes of fruit quality and fruit granulation in the late maturing navel orange fruit ripening period (from December to June) at different altitudes (520 m,380 m,220 m) in Zigui County of the Three Gorges Reservoir were investigated. The effect of the navel orange fruits bagging in the winter to prevent fruit granulation was studied. Results showed that fruit granulation of the late maturing navel orange in the Rservoir Area was mainly caused by the low temperature in winter. Fruit quality of high altitude (520 m) was significantly lower than that of middle and low elevations (380 m,220 m). At high altitude (520 m) ,the soluble solids content and solid acid ratio,water content,juice rate were low,and the fruit color was poor. Fruit water content and fruit granulation decreased with the harvest stage. The ratio of fruit granulation was high at the stage of flowering (late April) and shoot growth (early May),reaching 50.0% and 38.8%,respectively. The index of fruit granulation increased. The degree of fruit granulation aggravated gradually. A few fruit slightly granulated in middle June at low elevations. Fruit granulation didn’t occur in other time at low elevations.Fruits bagging helps reduce or prevent fruit granulation. The rate of fruit granulation decreased to 6.0%,while the content of fruit edible rate,fruit juice rate and soluble solids increased significantly,and fruit coloring and internal quality was improved significantly as well. 