Supercritical carbon dioxide (scCO(2)) micro-emulsion systems were formed in a custom-made volume-variable optical phase equilibrium cell, by employing Ls-36 (dodecyl(poly(ethylene-methylethylene glycol)) ether) as a surfactant, ethanol (EtOH) as a cosolvent, and propane-1,3-diol (1,3-PDO) as a disperse phase in the CO2 continuous phase. The phase behaviors of the ternary system of Ls-36 + CO2 + EtOH, quaternary system of Ls-36 + CO2 + EtOH + H2O, and quinary system of Ls-36 + CO2 + EtOH + 1,3-PDO + H2O were investigated in the temperature range of 303.05 K to 323.25 K and pressure range of 7.81 MPa to 18.99 MPa were studied. Thermodynamically stable microemulsion can be formed by controlling the operating pressure and temperature to selectively extract the 1,3-PDO from its dilute aqueous solution. It was found that a higher concentration of Ls-36 was more beneficial to the solubilization of 1,3-PDO. The results may provide useful thermodynamics data for industrial design and a feasible basis and practical guidance for selectively extracting 1,3-PDO from fermentation broth efficiently in industry.