To investigate the effects of ultrasound-assisted immersion freezing on the osmotic mass transfer characteristics of blueberries， air freezing， immersion freezing and ultrasound-assisted immersion freezing were applied to blueberries. The freezing rate， water distribution， calcium content， anthocyanin content， cell membrane permeability and malondialdehyde content were measured and analyzed. The results showed that compared with air freezing and immersion freezing， ultrasonic-assisted immersion freezing significantly shortened the freezing time of blueberries， and the drip loss after thawing was the lowest， 8.26%， and the water distribution was more similar to that of fresh blueberries. Ultrasonic promoted the permeation migration of exogenous calcium， and the calcium content in whole fruit and pulp increased significantly (P﹤0.05)； the hardness was better preserved， but the retention rate of anthocyanin decreased， and the cell membrane permeability and malondialdehyde content decreased significantly (P<0.05)， which were 54.65% and 9.15 nmol/g FW， respectively. In conclusion， ultrasound-assisted immersion freezing can not only improve freezing rate， reduce lipid membrane peroxidation and maintain the integrity of cell membrane， but also promote the infiltration of solution solute into food.