Crude oil is the most exploited energy source and the best way to increase the yield of oil recovery is the use of middle‐phase microemulsions. But the consecutive formation of water‐in‐oil emulsions needs oil–water separation. Reversible middle‐phase microemulsions were prepared with tetradecane (equivalent alkane for crude oil from Xinjiang oilfields, China) and aqueous solutions containing 1‐pentanol, N,N‐dimethyltetradecylamine and NaCl, and stimulated with CO2. By adding and removing CO2, the conductivity of aqueous solutions without NaCl increases from 20 μS/cm to 3.6 mS/cm reversibly. Additionally, the surface and interfacial tensions of aqueous solution show reversible changes. The middle‐phase microemulsion is stable in CO2 atmosphere. After removing CO2, it becomes separated into oil and aqueous phases. However, by sparging CO2 and standing for 2 days, it becomes middle‐phase microemulsion again. This research is expected to launch a brand‐new avenue for the CO2‐stimulated reversible microemulsification. [ABSTRACT FROM AUTHOR]