Abstract: On line measurement of pulsed column parameters by air purge is studied. The measuring deviation for two phase interface is within ±4 mm. The relative measuring deviations are within 2 % for pulsation frequency and within ±5 % for hold up, respectively. A good linear relationship between apparent pulsation amplitude and an empirical parameter S, which is derived from the signal response curve, is found. The dependency of real pulsation amplitude on apparent pulsation amplitude and frequency is determined experimentally. The real pulsation amplitude in column can be measured by air purge.