Abstract: In order to useΦ20 mm centrifugal extractors for experimental study of the 2A contactor of Purex process, the hydraulic properties of such a centrifugal extractor were investigated under the working conditions prescribed by the process parameters of the 2A contactor. By using 30%TBP/kerosene-HNO₃ as the extraction system and fixing the heavy phase weir diameter to 10.8 mm, the influence of aqueous-to-organic phase flow ratio (A∶O), two-phase total flow rate, and rotation speed of the rotor on the entrainment of liquids from both light and heavy phase outlet, and on the volume of liquid in the mixing zone and that in the rotator were examined. The experimental results show that when the A∶O is 1∶1 and the total flow rate is less than 70.0 mL/min, or the A∶O is 5∶1 and the total flow rate is less than 28.8 mL/min, and the rotation speed is greater than 3 000 r/min, such type of centrifugal extractor works in a stable operational condition, liquids from both light and heavy phase outlet are not entrained. The liquid volume of the mixing zone is about 5.1 mL, and the total liquid volume in the rotor is about 12.3 mL. The two phase contact time is calculated to be t = 5.1×60/v_t, where v_t is the total flow rate. The results indicate that this type of centrifugal extractor can meet the requirements for process research of 2A contactor of Purex process.