Four distinct types of citrus fruits, specifically 'Juxiangzao' satsuma mandarin, 'Yuanfeng' navel orange, 'Qianyang Bingtangcheng' sweet orange and 'Shatian Yu', were used as experimental materials to investigate the developmental patterns of juice sacs in different citrus types. This was achieved by comparing their microstructural characteristics and developmental processes. To explore the regulatory effects of gibberellin on juice sac development, 'Qianyang Bingtangcheng' sweet orange was treated with gibberellin(GA3) during the cell division phase. The results showed that juice sac primordia differentiated at the flower bud stage and expanded significantly after anthesis. Afterward, juice sac number increased rapidly within one month post-anthesis. Specifically, the average number of juice sacs per segment of 'Juxiangzao' satsuma mandarin was 219, with an average volume of 51.22 mm3, which was characterized by their large individual size and rapid development. In contrast, the average number of juice sacs per segment of ‘Shatian Yu’ was approximately 415, with an average volume of 58.08 mm3. These sacs were the largest among the studied citrus types but exhibited a slower developmental rate. The average numbers of juice sacs per segment of ‘Yuanfeng’ navel orange and ‘Qianyang Bingtangcheng’ sweet orange were approximately 429 and 448, with average individual juice sac volumes of 35.53 mm3 and 7.24 mm3, respectively. Both cultivars exhibited a relatively long juice sac developmental period. When treated with GA? during the cell division stage, the fruit volume exhibited a significant increase in size, with the number of juice sacs per segment increasing by 20.3%-22.3%, thereby promoting fruit enlargement. This promotion in fruit size was primarily attributed to an increase in juice sac number rather than their individual volume. In summary, the size of citrus fruit was closely associated with both the number and volume of juice sac, and the application of GA3 during the cell division phase promote juice sac differentiation and affected the final fruit size.