In order to reveal the enhancement mechanism of subcritical CO₂ extraction by ultrasonic and describe the mass transfer enhanced with ultrasonic,some experiments were carried out and the data were fitted with the help of a kinetic extraction model.Then,the cavitations threshold at variable temperature and pressure were obtained based on theoretical calculation.Moreover,the cativation in the subcriticalCO₂ extraction enhanced by ultrasonic was investigated according to the results of the experiments.The results show that（1） the established kinetic model fits the extraction data well;（2） the difference in E∞ and k values between the extractions with and without ultrasonic enhancement also confirm the obvious enhancement effect of ultrasonic for the mass transfer in subcritical CO₂ extraction;（3） the occurrence of ultrasonic cavitation is rather easy at relatively high temperature and low pressure;（4） the cavitation occurs even under the conditions that cavitation is theoretically unavailable,for which there is no reasonable explanation;and（5） the enhancement is mainly due to the cavitation effect and the enhanced mass transfer.