Abstract: Changes of ratios of various parts of fruit weight to the whole fruit，peel thickness，contents of total soluble solids，sugars，titratable acid，carotenoids and flavonoids，and antioxidant capacity in developing satsuma mandarin（Citrus unshiu ‘Miyagawa Wase’）fruit were measured under greenhouse delayed harvest condition. The results showed the ratios of peel and segment epidermis to the whole fruit were at relatively low levels during periods of delayed cultivation；While the ratios of juice sacs to the whole fruit were at relatively high levels. The contents of sucrose，total sugar，total soluble solids，carotenoids and flavonoids increased with the delay of harvest time. The antioxidant capacity of juice sacs was higher in delayed harvest fruits than that in normal harvest fruits. However，in the later periods of delayed harvest（especially in February of next year），the ratios of segment epidermis and peel to the whole fruit turned to increase with the delay of harvest time，the ratio of juice sacs converted to decrease accordingly，peel became thicker and thicker. The contents of glucose and fructose began to decline rapidly. The contents of carotenoids and flavonoids and the antioxidant capacity also slightly decreased in the late of delayed harvest. These results suggested delayed harvest was an effective measure for improvement fruit quality of satsuma mandarin，but not later than the middle of January harvest，too late may reduce fruit quality.

Key words: satsuma mandarin, delayed harvest, fruit quality, antioxidant capacity