Decompressing inner ebullition (DIE) is a novel method and it can achieve a rapid extraction at lower temperature for active constituents of medical plants. In this work, DIE was employed to extract puerarin from puerarin lobata (Wind.) Ohwi (PLO). The extraction conditions were investigated according single factor analysis. Experiment results showed that the extraction yield of puerarin reached a maximum value when the ethanol mass concentration in the aqueous solution immersing the PLO was 60%, the amount of ethanol solution for premaceration and of water for extraction were 1.6 and 10 mL.g(-1) of PLO, respectively, the operation gauge pressure was -0.084 MPa, and the extraction temperature was 50 degrees C. Under the optimal conditions, the extraction kinetics of DIE was studied. The mass transfer coefficient of DIE ranged between 0.09 and 0.13 s(-1), which is 183 times greater than that of ultrasonic assistant extraction under the same conditions, and its extraction activation energy Delta E is 10.86 kJ.mol(-1). Also, the thermodynamics properties in the extraction process of DIE at 50 degrees C were also calculated, the enthalpy change Delta H is 58.76 kJ.mol(-1), the entropy change AS is 224.50 J.mol(-1)K(-1), and Gibbs free energy Delta G is -13.73 kJ.mol(-1), respectively. The extraction of DIE belongs to a spontaneous process with endothermic and entropy increasing.