Abstract: Theoretical result indicates that the time-averaged pressure drop of column weight, measured by air-purge method, increases with time at flooding point of pulsed extraction column, and it is experimentally proved in 50 mm discs and doughnuts pulsed extraction column for the 30%TBP/kerosene-1 mol•L^-1 HNO₃ system. Based on above results, the method is given when the direct determination of flooding for the extraction column by air-purge method is used in industry.