Abstract: The axial profile of gas holdups was measured using a γ-ray densitometry in the pressurized bubble column,0.3 m in diameter and 6.6 m in height.The principle of γ-ray measurement and data processing is discussed.The axial profile of gas holdups and its average value in two-phase system were obtained in the churn-turbulent flow regime with a gas velocity up to 0.40 m•s^-1 and a system pressure up to 1.0 MPa, which are in agreement with results obtained by differential pressure method.The effects of superficial gas velocity, liquid surface tension, liquid viscosity and system pressure on the axial profile of gas holdups were investigated.It is shown that the gas holdup decreases with the increasing liquid viscosity and liquid surface tension, and increases with the increase of pressure and superficial gas velocity.