Phase behaviors of scCO(2) microemulsions of the quaternary system of 2,6,8-trimethyl-4-nonyl ether (TMN-6) + CO2 + ethyl alcohol (EtOH) + H2O and the quinary system of TMN-6 + CO2 + EtOH + propane-1,3-diol (1,3-PDO) + H2O were investigated in a volume-variable high-pressure view cell at temperatures from (302.85 to 317.25) K and at pressures of (6.6 to 12.4) MPa. In these systems, a commercially available nonionic surfactant poly(ethylene glycol) TMN-6 was used as the surfactant and ethanol as the cosurfactant. 1,3-PDO dilute aqueous solutions of 0.025, 0.050, and 0.075 mass fraction were used as model compounds to simulate the real fermentation broth. The results showed that a thermodynamically stable microemulsion can be formed under mild conditions by controlling the operating pressures and temperatures. 1,3-PDO was able to be extracted selectively from the dilute aqueous solution by using scCO(2) microemulsion at appropriate temperatures and pressures. This work provides basic thermodynamic data for industrial design and a feasible basis for selective solubilizing 1,3-PDO from fermentation broth.