Puffing is a common physiological disease of mandarin fruits. Based on reviewing literatures at home and abroad， it is clear that the peels of citrus fruits puffing is rough， foamy， thick and perishable. The sponge layer is loose， collapsed and disordered. There is a large gap between the peel and the pulp due to its separation. The content of sugar and acid in the pulp is low. The valve is thick and hard. The juice sac is dehydrated and hardened. The conditions for the occurrence of citrus fruit puffing are described from the aspects including fruit size， maturity， mineral nutrition， climate factors， etc.. The mechanisms of the occurrence of citrus fruit puffing are revealed from the aspects including cytological level， physiological level and molecular level. According to the “asynchronous development” mechanism of citrus fruit puffing， it is urgent to carry out in-depth studies from three levels including source-sink supply， competition suppression and integrated coordination， and strive to solve the problems of citrus fruit puffing through combining “ integrated coordination” with “targeted regulation”.