Abstract: Downhole detection of gas kick is an advanced concept and technology trend to ensure its early detection and early warning. This experimental system proposed in this paper includes three parts: simulated wellbore, gas-liquid control system, and low-frequency acoustic signal trigger/receiving system. And the relevant data processing method is developed. This experimental system can directly show the bubble migration and distribution characteristics after gas kick, and it can observe the change of phase velocity and attenuation of low-frequency acoustic waves due to gas kick, which is helpful for its detection. The measurement results of the experimental system are in good agreement with the predictions of theoretical models. Therefore, this experimental system can be used to investigate the low-frequency acoustic properties of bubbly liquids at different frequencies, gas fraction, and working fluid properties (such as density and viscosity). This new experimental system provides a basic platform for the research of gas kick downhole detection based on the characteristics of low-frequency acoustic waves.