AbstractExperiments were conducted to investigate the inner structure of gas–liquid flow in airlift pumps by a laser Doppler velocimetry (LDV) system and a laser‐high speed photography. The measured central plane of the riser pipe was illustrated by a laser device, and the corresponding gas–liquid flow in this plane was recorded by a high speed camera. The results showed it was the wispy annular flow, rather than the annular flow, dominated the pump performance under a high gas flow rate. This wispy annular had a thick film with a maximal value 0.2 times of pipe diameter, and it kept pump working with a high output liquid flow rate at large gas flow rates. Moreover, new flow regime maps were presented with a function of accurately estimating the flow regime transition and presenting the airlift pump performance.