Abstract: This study investigates the pressure and flow characteristics of gas-liquid two-phase flow in an air-water medium using an airlift pump. The analysis is based on the time domain, power spectral density (PSD), and probability density function (PDF) of the pressure signal to identify different flow regimes. The results indicate that, except for the vicinity of ejector, the average local pressure at other locations gradually increases with increasing gas velocity, reaching a peak and then decreasing. The peak value shifts towards the right and the rate of increase becomes larger as the submergence ratio decreases. The liquid velocity increases rapidly with increasing gas velocity, reaching a peak and then remaining nearly constant. The maximum enhancement efficiency, which is about 49%, does not occur at the same gas velocity as the maximum liquid velocity. At different gas flow rates, the presence of bubble flow, cap flow, slug flow, churn flow and annular flow was observed. Different flow regime can be identified through estimation parameters such as PSD and PDF. Especially, the lower the immersion rate, the more favorable it is for the formation of gas slugs (slug flow). The results of this study can provide technical support for the gas-liquid-solid three-phase flow pressure drop and efficiency model and the future study of gas-liquid two-phase flow.