Abstract: In order to explore the influence of ultrasonic treatments on heat and mass transfer during fruits and vegetables processing, apples were taken as the research object, and ultrasonic assisted low temperature water bath test and ultrasonic water precooling assisted vacuum freeze drying tests of apple slices were respectively carried out combined with ultrasonic treatment technology of different frequencies（40, 68, 80 kHz）. The results showed that ultrasonic assisted low temperature water bath could effectively strengthen the heat exchange between apples and cold water. When the frequency was 80 k Hz, the cooling coefficients in the middle and near the core of apple pulp were increased by 35.3%and 28.6%, respectively, compared with the control group. After ultrasonic water precooling treatment, the effective water diffusion coefficients in vacuum freeze-drying process were increased by 51.6%（ultrasonic frequency of 40 kHz）,55.9%（ultrasonic frequency of 68 kHz） and 58.7%（ultrasonic frequency of 80 kHz）, respectively, compared with the control group.